BIOPHARMACEUTICALS BIOCHEMISTRY AND BIOTECHNOLOGY - PART 5 doc

Ongoing clinical trials are likely to expand considerably the medical uses of these regulatory molecules over the next few years. While at least some of these potential therapeutic applications were appreciated as far back as the late 1950s, initial therapeutic application was rendered impractical due to the extremely low 208 BIOPHARMACEUTICALS Figure 4.6. Outline of how the eIF-2a protein kinase system promotes an anti-viral effect levels at which they are normally produced in the body. Large-scale purification from sources such as blood was non-viable. Furthermore, IFNs exhibit species preference, and in some cases, strict species specificity. This rend ered necessary the clinical use of only human-derived interferons in human medicine. Up until the 1970s, IFN was sourced, in small quantities, direct ly from human leukocytes obtained from transfused blood supplies. This ‘interferon’ preparation a ctually consisted of a mixture of various IFN-as, present in varying amounts, and was only in the regions of 1% pure. However, clinical studies undertaken with such modest quantities of impure IFN preparations produced encouraging results. The production of IFN in significant quantities first became possible in the late 1970s, by means of mammalian cell culture. Various cancer cell lines were found to secrete IFNs in greater than normal quantities, and wer e amenable to large-scale cell culture due to their transformed nature. Moreover, hybridoma technology facilitated development of sensitive IFN immuno- assays. The Namalwa cell line (a specific strain of human lymphoblastoid cells) became the major industrial source of IFN. The cells were propagated in large animal cell fermenters (up to 8000 litres) and subsequent addition of an inducing virus (usually the Sendai virus) resulted in production of significant quantities of leukocyte inter feron. Subsequent analysis showed this to consist of at least eight distinct IFN-a subtypes. Wellferon is the trade name given to one such approved product. Produced by large-scale mammalian (lymphoblastoid) cell cultures, the crude preparation undergoes extensive THE CYTOKINES — THE INTERFERON FAMILY 209 Table 4.8. Interferon-based biopharmaceuticals approved to date for general medical use Product Company Indication Intron A (rIFN-a-2B) Schering Plough Cancer, genital warts, hepatitis PegIntron A (PEGylated rIFN-a-2B) Schering Plough Chronic hepatitis C Viraferon (rIFN-a-2B) Schering Plough Chronic hepatitis B and C ViraferonPeg (PEGylated rIFN-a-2B) Schering Plough Chronic hepatitis C Roferon A (rhIFN-a-2A) Hoffman–La-Roche Hairy cell leukaemia Actimmune (rhIFN-g-IB) Genentech Chronic granulomatous disease Betaferon (rIFN-b-1B, differs from human protein in that Cys 17 is replaced by Ser) Schering AG Multiple sclerosis Betaseron (rIFN-b-1B, differs from human protein in that Cys 17 is replaced by Ser) Berlex Laboratories and Chiron Relapsing, remitting multiple sclerosis Avonex (rhIFN-b-1A) Biogen Relapsing multiple sclerosis Infergen (rIFN-a, synthetic type I interferon) Amgen (USA) Yamanouchi Europe (EU) Chronic hepatitis C Rebif (rh IFN-b-1A) Ares Serono Relapsing/remitting multiple sclerosis Rebetron (combination of ribavirin and rhIFN-a-2B) Schering Plough Chronic hepatitis C Alfatronol (rhIFN-a-2B) Schering Plough Hepatitis B, C and various can- cers Virtron (rhIFN-a-2B) Schering Plough Hepatitis B and C Pegasys (PEGinterferon a-2A) Hoffman La Roche Hepatitis C Vibragen Omega (rFeline interferon-o) Virbac Veterinary (reduce mortality/ clinical signs of canine parvovirusis) chromatographic purification, including two immuno-affinity steps. The final product contains nine IFN-a subtypes. Recombinant DNA technology also facilitated the production of IFNs in quantities large enough to satisfy potential medical needs. The 1980s witnessed the cloning and expression of most IFN genes in a variety of expression systems. The expression of specific genes obviously yielded a product containing a single IFN (sub)-type. Most IFNs have now been produced in a variety of expression systems including E. coli, fungi, yeast and also some mammalian cell lines su ch as Chinese hamster ovary (CHO) cell lines and monkey kidney cell lines. Most IFNs currently in medical use are recombinant human (rh) products produced in E. coli. The inability of E. coli to carry out post- translational modifications is in most instances irrelevant, as the majority of human IFN-as, as well as IFN-b, are not normally glycosylated. While IFN-g is glycosylated , the E. coli-derived unglycosylated form displays a biological activity identical to the native human protein. The production of IFN in recombinant microbial systems obviously means that any final product contaminants will be microbial in nature. A high degree of purification is thus required to minimize the presence of such non-human substances. Most IFN final product preparations are in the region of 99% pure. Such purity levels are achieved by extensive chromatographic purification. While standar d techniques such as gel filtration and ion-exchange are extensively used, reported IFN purification protocols have also entailed the use of various affinity techniques, e.g. using anti-IFN monoclonal antibodies, reactive dyes or lectins (for glycosylated IFNs). Hydroxyapatite, metal-affinity and hydrophobic interaction chromatography have also been employed in purification protocols. Many production columns are run in fast protein or high-performance liquid chromotography (FPLC or HPLC) format, yielding improved and faster resolution. Immunoassays are used to detect and quantify the IFNs during downstream processing, although the product (particularly the finished product) is also usually subjected to a relevant bioassay. The production and medical uses of selected IFNs are summarized in the sections below. Production and medical uses of IFN-a Clinical studies unde rtaken in the late 1970s, with multi-component, impure IFN-a preparations, clearly illustrated the therapeutic potential of such interferons as an anti-cancer agent. These studies found that IFN-a could induce regression of tumours in significant numbers of patients suffering from breast cancer, certain lymphomas (malignant tumour of the lymph nodes) and multiple myeloma (malignant disease of the bone marrow). The IFN preparations could also delay recurrence of tumour growth after surgery in patients suffering from osteogenic sarcoma (cancer of connective tissue involved in bone formation). The first recombinant IFN to become available for clinical studies was IFN-a2 A, in 1980. Shortly afterwards the genes coding for additional IFN-as were cloned and expressed, allowing additional clinical studies. The anti-viral, anti-tumour and immuno-modulatory properties of these IFNs assured their approval for a variety of medical uses. rhIFN-as manufactured/ marketed by a number of companies (Table 4.8) are generally produced in E. coli . Clinical trials have shown the recombinant IFNs to be effective in the treatment of various cancer types, with rhIFN-a2A and -a2B both approved for treatment of hairy cell leukaemia. This is a rare B lymphocyte neoplasm for which few effective treatments were previously available. Administration of the rIFNs promotes significant regression of the cancer in up to 90% of patients. 210 BIOPHARMACEUTICALS Schering Plough’s rhIFN a-2B (Intron A) was first approved in the USA in 1986 for treatment of hairy cell leukaemia, but is now approved for use in more than 50 countries for up to 16 indications (Table 4.9). The producer microorganism is E. coli, which harbours a cytoplasmic expression vector (KMAC-43) containing the IFN gene. The gene product is expressed intracellularly and in soluble form. Intron A manufacturing facilities are located in New Jersey and Brinny, County Cork, Ireland. Upstream processing (fermentation) and downstream processing (purification and formula- tion) are physically separat ed by being undertaken in separate buildings. Fermentation is generally undertaken in specially designed 42 000 litre stainless steel vessels. After recovery of the product from the cells, a number of chromatographic purification steps are undertaken, essentially within a large cold room adapted to function under clean room conditions. Crystallization of the IFN-a-2B is then undertaken as a final purification step. The crystalline product is redissolved in phosphate buffer, containing glycine and human albumin as excipients. After aseptic filling, the product is normally freeze-dried. Intron A is usually sold at five commercial strengths (3, 5, 10, 25 and 50 million IU/vial). More recently, a number of modified recombinant interferon products have also gained marketing approval. These include PEGylated interferons (PEG IntronA and Viraferon Peg (Table 4.8) and the synthetic IFN product, Infergen). PEGylated interferons are generated by reacting purified a-IFNs with a chemically activated form of polyethylene glycol (Chapter 3). Activated methoxypolyethylene glycol is often used, which forms covalent linkages with free amino groups on the IF N molecule. Molecular mass analysis of PEGylated IFNs (e.g. by mass spectroscopy, gel filtratio n or SDS–PAGE) indicate that the a pproved PEGylated products consist predominantly of monoPEGylated IFN molecules, with small amounts of both free and diPEGylated species also being present. The intrinsic biological activity of PEGylated and non-PEGylated IFNs are essentially the same. The PEGylated product, however, displays a significantly prolonged plasma half-life (13– 25 h as compared to 4 h for unPEGylated species). The prolonged half-life appears to be mainly due to slower elimination of the molecule, although PEGylation also appears to decrease systemic absorption from the site of injection following subcutaneous administration. Infergen (interferon acon-1, or consensus interferon) is an engineered IFN recently approved for the treatment of hepatitis C (Table 4.8). The development of Infergen entailed initial THE CYTOKINES — THE INTERFERON FAMILY 211 Table 4.9. Some of the indications (i.e. medical conditions) for which intron A is approved. Note that the vast majority are either forms of cancer or viral infections Hairy cell leukaemia Laryngeal papillomatosis* Renal cell carcinoma Mycosis fungoides** Basal cell carcinoma Condyloma acuminata *** Malignant melanoma Chronic hepatitis B AIDS-related Kaposi’s sarcoma Hepatitis C Multiple myeloma Chronic hepatitis D Chronic myelogenous leukaemia Chronic hepatitis, non-A, Non-Hodgkin’s lymphoma non-B/C hepatitis *Benign growths (papillomas) in the larynx. **A fungal disease. ***Genital warts. sequence comparisons between a range of IFN-as. The product’s amino acid sequence reflects the most frequently occurring amino acid resid ue in each corresponding position of these native IFNs. A DNA sequence coding for the product was synthes ized and inserted into E. coli. The recombinant product accumulates intracellularly as inclusion bodies (Chapter 3). Large-scale manufacture entails an initial fermentation step. After harvest, the E. coli cells are homogenized and the inclusion bodies recovered via centrifugation. After solubilization and re- folding, the interferon is purified to homogeneity by a combination of chromatographic steps. The final product is formulated in the presence of a phosphate buffer and sodium chloride. It is presented as a 30 mg/ml solution in glass vials and displays a shelf-life of 24 months when stored at 2–88C. When compared on a mass basis, the synthetic interferon displays higher antiviral, antiproliferative and cytokine-inducing activity than do native type I interferons. Ongoing clinical trials continue to assess the efficacy of rIFN preparations in treating a variety of cancers. Some trials suggest that treatments are most effective when administered in the early stages of cancer development. rhIFN-as have also proved effective in the treatment of various viral conditions, most notably viral hepatitis. Hepatitis refers to an inflammation of the liver. It may be induced by toxic substances, immunological abnormalities or by viruses (infectious hepatitis). The main viral causative agents are: . hepatitis A virus (hepatitis A); . hepatitis B virus (hepatitis B, i.e. classical serum hepatitis); . hepatitis C virus (hepatitis C, formerly known as classical non-A, non-B hepatitis); . hepatitis D virus (hepatitis D, i.e. delta hepatitis); . hepatitis E virus (hepatitis E, i.e. endemic non-A, non-B hepatitis); . hepatitis GB agent. This disease may be acute (rapid onset, often accompanied by severe symptoms but of brief duration) or chronic (very long duration). Hepatitis A is common, particularly in areas of poor sanitation, and is transmitted by food or drink contam inated by a sufferer/carrier. Clinical symptoms include jaundice, and are usually mild. A full recovery is normally recorded. Hepatitis B is transmitted via infected blood. Symptoms of acute hepatitis B include fever, chill, weakness and jaundice. Most sufferers recover from such infection, although acute liver failure and death sometimes occur; 5–10% of sufferers go on to develop chronic hepatitis B. Acute hepatitis C is usually mild and asymptomatic. However, up to 90% of infected persons go on to develop a chronic form of the condition. Hepatitis D is unusual in that it requires the presence of hepatitis B in order to replicate. It thus occurs in some persons concomit antly infected with hepatitis B virus. Its clinical symptoms are usually severe, and can occur in acute or chronic form. Chronic forms of hepatitis (in particular B, C and D) can result in liver cirrhosis and/or hepatocellular carcinoma. Thi s occurs in up to 20% of chronic hepatitis B sufferers, and up to 30% of chronic hepatitis C sufferers. The scale of human suffering caused by hepatitis on a worldwide basis is enormous. Approximately 5% of the global population suffer from chronic hepatitis B. An estimated 50 million new infections occur each year. Over 1.5 million of the 300 million carriers worldwide die annually from liver cirrhosis and hep atocellular carcinoma. IFN-a2B is now approved in the USA for the treatment of hepatitis B and C. Clinical studies undertaken with additional IFN-a preparations indicate their effectiveness in managing such conditions, and several such products are also likely to gain regulatory approval. IFN-a2A, when administered three times weekl y for several weeks/months, was found effective in treating several forms of hepatitis. Remission is observed in 30–45% of patients 212 BIOPHARMACEUTICALS suffering from chronic hepatitis B, while a complete recovery is noted in up to 20% of cases. The drug induces sustained remission in up to 30% of patients suffering from chronic hepatitis C, but can ease clinical symptoms of this disease in up to 75% of such patien ts. Ongoi ng studies also indicate its efficacy in treating chronic hepatitis D, although relapse is frequently observed upon cessation of therapy. The drug is normally administered by the intramuscular (i.m.) or subcutaneous (s.c. — directly beneath the skin) injection. Peak plasma concentrations of the IFN are observed more quickly upon i.m. injection (4 h versus 7.5 h). The elimination half-life of the drug ranges from 2.5 to 3.5 h. IFN-a preparations have also proved efficacious in the treatment of additional viral-induced medical conditions. rhIFN-a2B, as well as IFN-an3 are already approved for the treatment of sexually transmitted genital warts, caused by a human papilloma virus. While this condition is often unrespo nsive to various additional therapies, direct injection of the IFN into the wart causes its destruction in up to 70% of patients. Another member of the papilloma virus family is associated with the development of benign growths in the larynx (laryngeal papillomatosis). This condition can be successfully treated with IFN-a preparations, as can certain papilloma- related epithelial cell cancers, such as cervical intraepithelial neoplasm (epithelial cells are those that cover all external surfaces of the body, and line hollow structures — with the exception of blood and lymph vessels). IFN-a’s ability to combat a range of additional virally-induced diseases, including AIDS, is currently being appraised in clinical trials. Medical uses of IFN-b RhIFN-b has found medical application in the treatment of relapsing–remitting multiple sclerosis (MS), a chronic disease of the nervous system. This disease normally presents in young adults (more commonly women) aged 20–40. It is characterized by damage to the myelin sheath, which surrounds neurons of the central nervous system, and in this way compromises neural function. Clinical presentations include shaky movement, muscle weakness, paralysis, defects in speech, vision and other higher mental functions. The most predominant form of the condition is characterized by recurrent relapses followed by remission. MS appears to be an autoimmune disease, in which elements of immunity (mainly lymphocytes and macrophages) cooperate in the destruction of the myelin. What triggers onset of the condition is unknown, although genetic and environmental factors (including viral infection) have been implicated. IFN-b preparations approved for medical use to date include Betaferon, Betaseron, Avonex and Rebif (Table 4.8). The former two products are produced in recombinant E. coli cells, whereas the latter two are produced in CHO cell lines. Manufacture using E. coli generates a non-glycosylated product, although lack of native glycosylation does not negatively affect its therapeutic efficacy. Typically, IFN-b-based drugs reduce the frequency of relapses by about 30% in many patients. In some instances, a sustained reduction in the accumulation of MS brain lesions (as measured by magnetic resonance imaging) is also observed. However, there is little evidence that IFN-b significantly alters overall progression of the disease. A summary overview of the production of one such product (Betaferon) is presented in Figure 4.7. The molecular mechanism by which IFN-b induces its therapeutic effect is complex and not fully understood. It is believed that the pathology of multiple sclerosis is linked to the activation and proliferation of T lymphocytes specific for e pitopes found on specific myelin antigens. Upon migration to the brain, these lymphocytes trigger an inflammatory response mediated by the production of pro-inflammatory cytokines, most notably IFN-g, IL-1, IL-2 and TNF-a. The inflammatory response, in addition to other elements of immunity (e.g. antibodies and THE CYTOKINES — THE INTERFERON FAMILY 213 complement activation), results in the destruction of myelin surrounding neuronal axons. IFN-b probably counteracts these effects in part at least by inhibiting production of IFN-g and TNF- a and hence mediating downregulation of the pro-inflammatory response. Medical applications of IFN-c The most notable medical application of IFN-g relates to the treatment of chronic granulomatous disease (CGD), a rare genetic condition, with a population incidence of 1 in 250 000–1 in a million. Phagocytic cells of patients suffering from CGD are poorly capable or incapable of ingesting or destroying infectious agents such as bacteria or protozoa. As a result, patients suffer from repeated infections (Table 4.10), many of which can be life-threatening. 214 BIOPHARMACEUTICALS Figure 4.7. Overview of the manufacture of Betaferon, a recombinant human IFN-b produced in E. coli . The product differs from native human IFN-b in that it is unglycosylated and cysteine residue 17 had been replaced by a serine residue. E. coli fermentation is achieved using minimal salts/glucose media and product accumulates intracellularly in inclusion body (IB) form. During downstream processing, the IBs are solubilized in butanol, with subsequent removal of this denaturant to facilitate product re-folding. After two consecutive gel filtration steps excipients are added, the product is filled into glass vials and freeze- dried. It exhibits a shelf-life of 18 months when stored at 2–88C Phagocytes from healthy individuals are normally capable of producing highly reactive oxidative substances, such as hydrogen peroxide and hypochlorous acid, which are lethal to pathogens. Production of these oxidative species occurs largely via a multi-component NADPH oxidase system (Figure 4.8). CGD is caused by a genetic defect in any component of this oxidase system which compromises its effective functioning. In addition to recurrent infection, CGD sufferers also exhibit abnormal inflammatory responses, which include granuloma formation at various sites of the body (granuloma refers to THE CYTOKINES — THE INTERFERON FAMILY 215 Table 4.10. Some pathogens (bacterial, fungal and protozoal) whose phagocyte-mediated destruction is impaired in persons suffering from chronic granulomatous disease (CGD). Administration of IFN-g, in most cases, enhances the phagocytes’ ability to destroy these pathogens. These agents can cause hepatic and pulmonary infections, as well as genito- urinary tract, joint and other infections Staphylococcus aureus Plasmodium falciparum Listeria monocytogenes Leishmania donovani Chlamydia psittaci Toxoplasma gondii Aspergillus fumigatus Figure 4.8. Production of reactive oxygen species (ROS) by phagocytes. In addition to degrading foreign substances via phagocytosis, phagocytes secrete ROS into their immediate environment. These can kill microorganisms (and, indeed, damage healthy tissue) in the vicinity, thus helping control the spread of infection. The ROS are produced by an NADPH oxidase system, the main feature of which is a plasma membrane-based electron transport chain. NADPH represents the electron donor. The first membrane carrier is NADPH oxidase, which also requires interaction with at least two cytosolic proteins for activation. The electrons are passed via a number of carriers, including a flavoprotein, to cytochrome b 558 . This is a haem protein consisting of two subunits (22 kDa and 91 kDa). The cytochrome, in turn, passes the electrons to oxygen, generating a superoxide anion (O À ). The superoxide can be converted to hydrogen peroxide (H 2 O 2 ) spontaneously, or enzymatically, by superoxide dismutase (SOD). A genetic defect affecting any element of this pathway will result in a compromised ability/inability to generate ROS, normally resulting in chronic granulomatous disease (CGD). Over 50% of CGD sufferers display a genetic defect in the 91 kDa subunit of cytochrome b 558 a tissue outgrowth which is composed largely of blood vessels and connective tissue). This can lead to obstruction of various ducts, e.g. in the urinary and digestive tract. Traditionally, treatment of CGD entailed prophylactic administration of anti-microbial agents in an attempt to prevent occurrence of severe infection. However, affected individuals still experience life-threatening infections, requiring hospitalization and intensive medical care, as often as once a year. Attempts to control these infections rely on strong anti-microbial agents and leukocyte transfusions. Long-term administration of IFN-g to CGD patients has proved effective in treating/ moderating the symptoms of this disease. The recombinant human IFN-g used therapeutically is produced in E. coli, and is termed IFN-g1B. It displays identical biological activity to native human IFN-g, although it lacks the carbohydrate component. The product, usually sold in liquid form, is manufactured by Genentech, who market it under the tradename Actimmune. The product is administered on an ongoing basis, usually by s.c. injection three times weekly. In clinical trials its administration, when compared to a control group receiving a placebo, resulted in: . a reduction in the incidence of life-threatening infections by 50% or more; . a reduction in the incidence of total infections by 50% or more; . a reduction in the number of days of hospitalization by three-fold and even, when hospitalization was required, the average stay was halved. The molecular ba sis by which IFN-g induces these effects is understood, at least in part. In healthy individuals this cytokine is a potent activator of phagocytes. It potentiates their ability to generate toxic oxidative products (via the NADPH oxidase system), which they then use to kill infectious agents. In CGD sufferers IFN-g boosts flux through the NADPH oxidative system. As long as the genetic defect has not totally inactivated a component of the system, this promotes increased synthesis of these oxidative substances. IFN-g also promotes increased expression of IgG Fc receptors on the surfa ce of phagocytes. This would increase the phagocytes’ ability to destroy opsonized infectious agents via phagocytosis (Figure 4.9). Additional molecular mechanisms must also mediate IFN- g effects, as it promotes a marked clinical improvement in some CGD patients, without enhancing phagocyte activity. IFN-g’s demonstrated ability to stimulate aspects of cellular and humoral immunity (e.g. via T and B lymphocytes), as well as NK cell activity, is most likely respon sible for these observed improvements. IFN-g may also prove valuable in treating a variety of other conditions, and clinical trials for various indications are currently under way. This cytokine shows promise in treating leishmaniasis, a disease common in tropical and sub-tropical regions. The causative agent is a parasitic protozoan of the genus Leishmania. The disease is characterized by the presence of these protozoa inside certain immune cells, particularly macrophages. IFN-g appears to stimulate the infected macrophage to produce nitric oxide, which is toxic for the parasite. Additional studies illustrate that IFN-g stimulates phagocytic activity in humans suffering from various cancers, AIDS and lepromatous leprosy (leprosy is caused by the bacterium Mycobacterium leprae; lepromatous leprosy is a severe contagious form of the disease, leading to disfigurement). IFN-g may thus prove useful in treating such conditions. Interferon toxicity Like most drugs, administration of IFNs can elicit a number of unwanted side effects. Unfortunately, in some instances the severity of such effects can limit the maximum 216 BIOPHARMACEUTICALS recommended therapeutic dose to a level below that which might have maximum therapeutic effect. Administration of IFNs (in addition to many other cytokines) characteristically induces flu-like symptoms in many recipients. Such symptoms are experienced by most patients within 8 h of IFN-a administration. However, they are usually mild and are alleviated by concurrent administration of paracetamol. Tolerance of such effects also normal ly develops within the first few weeks of commencing treatment. THE CYTOKINES — THE INTERFERON FAMILY 217 Figure 4.9. Increased expression of IgG Fc receptors on phagocytes results in enhanced phagocytosis. These receptors will retain opsonized (i.e. antibody-coated) infectious agents at their surface by binding the Fc portion of the antibody. This facilitates subsequent phagocytosis [...]... additional cytokines, e.g both macrophages and fibroblasts are capable of producing several ILs, colony stimulating factors (CSFs) and platelet-derived growth factor (PDGF) Cell type Interleukins produced Macrophages Eosinophils Vascular endothelial cells Fibroblasts Keratinocytes IL-1, IL-3, IL-1, IL-1, IL-1, IL-6, IL -5 IL-6, IL-6, IL-6, IL-10, IL-12 IL-8 IL-8, IL-11 IL-8, IL-10 The sum total of biological responses... not interact directly with IL-2 It is sometimes known as gc (common) as it also appears to be a constituent of the IL-4, -7 , -9 , -1 3 and -1 5 receptors 226 BIOPHARMACEUTICALS Table 5. 3 Summary of the polypeptide constituents of the high-affinity human IL-2 receptor Receptor polypeptide constituent a b g Additional names P 55 Tac CD 25 P 75 CD122 P64 Molecular mass (kDa) 55 75 64 Heterodimeric complexes... human IL -5 reveals a two-domain structure, with each domain consisting of four a-helical stretches and one b-stretch consisting of two antiparallel b-strands The human IL -5 receptor consists of two transmembrane glycoprotein subunits The glycosylated 60 kDa a-chain binds IL -5 but is unable to induce direct signal transduction A b-chain, unable to bind IL -5 directly, is associated with the a-chain to... Cytokine Res 22 (5) , 50 5 51 6 Takatsu, K (1997) Cytokines involved in B cell differentiation and their sites of action Proc Soc Exp Biol Med 2 15( 2), 121–133 Taniguchi, T (19 95) Cytokine signalling through non-receptor protein tyrosine kinases Science 268, 251 – 255 Interferons Alberti, A (1999) Interferon acon-1 A novel interferon for the treatment of chronic hepatitis C Biodrugs 12 (5) , 343– 357 Belardelli,... status Indication Developing company Proleukin (rIL-2) Neumega (rIL-11) Approved (1992) Approved (1997) Chiron Corp Genetics Institute IL-2 IL-2 IL-4 Clinical trials Clinical trials Clinical trials Renal cell carcinoma Prevention of chemotherapy-induced thrombocytopenia HIV HIV and non-Hodgkin’s lymphoma Cancer (various) IL-4 and IL-13 IL-10 IL-18 IL-18 Clinical Clinical Clinical Clinical Asthma Inflammatory... factors and cytokines FASEB J 10(14), 157 8– 158 8 Li, J & Roberts, M (1994) Interferon-t and interferon-a interact with the same receptors in bovine endometrium J Biol Chem 269(18), 1 354 4–1 355 0 Lyseng-Williamson, K & Plosker, G (2002) Management of relapsing–remitting multiple sclerosis — defining the role of subcutaneous recombinant interferon-b-1a (Rebif) Dis Managem Health Outcomes 10 (5) , 307–3 25 THE... marrow cells and which represent the immature precursors to all blood cells (Chapter 6) IL-3 thus appears to play a central role in stimulating the eventual formation of various blood cell types, in particular monocytes, mast cells, neutrophils, basophils and eosinophils, from immature precursor cells in the bone marrow Several other cytokines (including IL-2, -4 , -5 , -6 , -7 , -1 1, -1 5 and CSFs) also... capable of producing IL-1 (see Table 5. 5), while IL-8 is produced by at least 10 distinct cell types On the other hand, IL-2, -9 and -1 3 are produced only by T lymphocytes Most cells capable of synthesizing one IL are capable of synthesizing several, and many prominent producers of ILs are non-immune system cells (Table 5. 1) Regulation of IL synthesis is exceedingly complex and only partially understood... cells and is presented as a purified product in freeze-dried format Excipients include phosphate buffer salts and glycine It is reconstituted (with water for injections) to a concentration of 5 mg/ml before s.c administration INTERLEUKIN -5 The biological activities of several other interleukins also render them likely candidates for therapeutic application IL -5 represents one such candidate IL -5 is a 1 15. .. lymphocytes (which also produce IL -5 ) and eosinophils in the airway mucosa The granular eosinophil contents may play an important role in mediating chronic bronchial inflammation While eosinophil production can be induced by IL-3, IL -5 and GM-CSF in vitro, only IL -5 plays this role effectively in vivo It follows that blocking the biological activity of IL -5 may CYTOKINES: INTERLEUKINS AND TUMOUR NECROSIS FACTOR . factors (CSFs) and platelet-derived growth factor (PDGF) Cell type Interleukins produced Macrophages IL-1, IL-6, IL-10, IL-12 Eosinophils IL-3, IL -5 Vascular endothelial cells IL-1, IL-6, IL-8 Fibroblasts. IL-2. It is sometimes known as gc (common) as it also appears to be a constituent of the IL-4, -7 , -9 , -1 3 and -1 5 receptors. CYTOKINES: INTERLEUKINS AND TUMOUR NECROSIS FACTOR 2 25 Figure 5. 1 IL-8 Fibroblasts IL-1, IL-6, IL-8, IL-11 Keratinocytes IL-1, IL-6, IL-8, IL-10 Table 5. 2. Some interleukin preparations approved for general medical use (or in clinical trials) and the disease(s)