Stimulation of lymphocyte proliferation by killed mycobacteria and other bacterial species

Abstract

Killed mycobacteria [Mycobacterium kansasii, M. smegmatis] and some mycobacterial fractions induced spleen cells from normal C3H mice to incorporate 3H-thymidine to a relatively high degree. Thymocytes under the same conditions were not activated. Incorporation of thymidine was significantly increased when mixtures of thymus and spleen cells were cultured in the presence of the inducers. A similar activation of spleen cells was displayed in the presence of gram-positive [Listeria monocytogenes, Staphylococcus aureus, .beta. hemolytic Streptococcus] and gram-negative [Escherichia coli, Serratia marcescens, Salmonella typhimurium] non-mycobacterial species. [This relates directly to the adjuvant and antitumor activity of BCG and other mycobacterial fractions.].