... ngÆmL)1macrophagecolony-stimulating factor (M-CSF)14 in RPMI 1640 medium(endotoxin < 0.01 endotoxin units (EU)ÆmL)1 in Limulustest; Biochrom, Berlin, Germany) containing 2 mml-gluta-mine, 100 UÆmL)1penicillin, and ... containing 2 mml-glutamine,100 UÆmL)1penicillin, and 100 lgÆmL)1streptomycin, added to the wells of a 96 well dish, and precipitated by addition of polyfect (1 lLin20lL serum-free DMEM) and incubationfor ... of the cultureplates for 10 min at 400 g and stored at )20 °C until deter-mination of cytokine content (see above).Determination of endotoxin activity by thechromogenic Limulus testEndotoxin...