Adjuvant activity of mycobacterial fractions. III. Adjuvant effect of cell wall of Mycobacterium bovis BCG on cell-mediated cytotoxicity in mice.

A quantitative assay and characterization of oil-attached cell wall of Mycobacterium bovis BCG (BCG-CWS) which stimulates cell-mediated immunity of spleen cells to alloantigens in mice were carried out by an in vitro cell-mediated cytotoxicity test using 51Cr-labeled target cells. C57BL/6J mice (H-2b) were immunized intraperitoneally with mastocytoma cells (H-2d) with or without oil-attached BCG-CWS. The cytotoxicity, comparable to that of spleen cells from mice immunized with mastocytoma cells (3 X 10(7)), could be induuced in spleens of mice immunized with a mixture of mastocytoma cells (10(4)) and oil-attached BCG-CWS. The enhancing effect persisted from 55 days or more after the alloantigenic immunization. Oil-attached BCG-CWS enhanced cell-mediated cytotoxicity of T cells in the spleen and the mesenteric lymph node, but not in the thymus. The cytotoxicity showed specificity toward the alloantigen used for immunization. In addition to BCG-CWS, the cell walls of Nocardia rubra and Corynebacterium diphtheriae PW8 and the peptidoglycolipids of Mycobacterium tuberculosis Aoyama B were found to be potent stimulants of cell-mediated cytotoxicity in mice. Oil-attached BCG-CWS did not enhance humoral response to mastocytoma cells but enhanced cell-mediated cytotoxicity when viable mastocytoma cells were used as antigen. The above result was supported by the fact that anti-hapten antibody response induced by viable trinitrophenyl (TNP)-mastocytoma cells (10(4)) plus oil-attached BCG-CWS did not increase to the maximum levels as was observed in mice immunized with a larger number of mastocytoma cells (3 X 10(7)) alone, while cell-mediated cytotoxicity induced by the same treatment increased to the maximum level obtained by immunization with mastocytoma cells (3 X 10(7)) alone.