IMMUNOLOGICAL ASPECTS OF TUBERCLE BACILLI

Abstract

In this symposium, the immunological aspects of tubercle bacilli were presented and the usefulness of tubercle bacilli as the materials for immunological study was discussed.
Dr. Yamamoto has studied on the mechanism of anti-tuberculosis protection in mice. When BCG cell walls which consist of adjuvant (BCG-CWS) and antigens (protein), were injected intravenously into mice as an oil-in-water emulsion, pulmonary granuloma were produced, and a close relationship was found between the degree of granuloma formation and protection against aerosol challenge with tubercle bacilli.
Dr. Yamamura and his group have clearly shown that experimental cavity formation in rabbits was due to the cell-mediated immune response of host to tubercle bacilli (and tubercle protein). The protein and lipid fractions were purified from mycobacterial cells and the cavity was produced by the in jection of the mixture of above protein (antigen) and lipid (adjuvant) fractions but not by each alone in rabbits. The biochemical and immunological mechanisms of experimental cavity formation in rabbits were investigated in detail.
The adjuvant activity and adjuvant-polyarthritogenicity were the characteristic biological acti vities of tubercle bacilli. Dr. Tanaka has reviewed the recent advance in these fields. Especially the details of N-acetylmuramyl-L-alanyl-D-isoglutamine (MDP) which was established to be the minimum adjuvant-active subunit of bacterial cell walls were summarized. MDP has also been shown to have adjuvant-polyarthritogenicity in rats.
Dr. Kishimoto has reported the selective suppression of anti-DNP IgE antibody response by preim munization of mice with DNP-con jugated mycobacterial cells, and the selective IgE suppression was shown to be due to the induction of DNP-reactive IgE class-specific suppressor T cells. Furthermore, he has obtained similar results by the administration of antigen (DNP or ovoalbumin)-conjugated 6-0 mycoloyl derivative of MDP. These results suggest the possibility of immunotherapy of allergic diseases.
Recently, the antitumor activity of BCG was shown in experimental tumor systems and human cancer. Dr. Ogura has presented the experimental and clinical results in experimental tumor systems and human lung cancer using BCG cell-wall skeleton (BCG-CWS). BCG-CWS was shown to be effective statistically for the prolongation of survival period of patients with lung cancer. The adjuvant activity on killer T cells and macrophage activation was considered to be immunological bases of anti tumor activity of BCG-CWS.
As shown in this symposium, tubercle bacilli are very interesting and useful materials for the study of immunology.