Two new inhibitory activities in blood of mice with delayed hypersensitivity, after challenge with specific antigen.

In addition to the activities associated with migration inhibitory factor and type II interferon, two other inhibitory activities have been found in the sera of mice infected intravenously with BCG and 3 weeks later challenged intravenously with old tuberculin. Growth of three bacteria, Streptococcus faecalis, Staphylococcus aureus, Pseudomonas aeruginosa, and one yeast, Candida albicans, was inhibited in vitro by a factor or factors in the serum. Also, hematopoiesis of mouse bone marrow cells in a soft agar medium was suppressed by the serum.