Biological characterization of guinea pig lymphotoxin production.

The generation of serum-free lymphotoxin by antigen-stimulated ovalbumin immune strain 2/N guinea pig peritoneal leukocytes in vitro is dependent upon a number of common variables in cell culture. Lymphotoxin production varies directly with antigen concentration, duration of antigen exposure and leukocyte culture, leukocyte density, and medium volume. The maximum concentration of lymphotoxin generated in the medium has a limiting value that is independent of antigen concentration, leukocyte density, and duration of antigen exposure or leukocyte culture, suggesting feedback control of lymphokine production. Optimal conditions for the reproducible maximum generation of guinea pig lymphotoxin were 10(7) oil-induced peritoneal leukocytes from immune animals cultured for 12-24 hr in 20 ml RPMI 1640 medium containing 100 micrograms ovalbumin/ml throughout the period of culture.