Compartmentalization of the cellular immune response to the recombinant 65 kDa protein of Mycobacterium bovis BCG in patients with tuberculous pleuritis.

The recombinant 65 kDa mycobacterial protein of M. bovis BCG has been shown to be immunodominant in mice immunized with M. tuberculosis. Little is known about reactivity to this antigen in patients with tuberculous pleuritis. In this study therefore, pleural effusion and autologous peripheral blood lymphocytes obtained from patients with tuberculous and nontuberculous pleuritis were stimulated in-vitro with the recombinant 65 kDa antigen. Proliferation was assessed by 3[H] thymidine incorporation. In addition, pleural effusion lymphocytes were activated in vitro with the 65 kDa antigen and tested for cytotoxic activity in 15-hr chromium-release assays. Pleural effusion lymphocytes obtained from a high percentage (56%) of patients with tuberculous pleuritis showed significant proliferative responses to the 65 kDa antigen, while the response in autologous peripheral blood lymphocytes was significantly lower. By contrast, pleural effusion lymphocytes obtained from patients with nontuberculous effusions were not reactive to the 65 kDa antigen. In addition, 65 kDa stimulated pleural effusion lymphocytes obtained from patients with tuberculous effusions showed antigen-specific lysis of autologous targets pulsed with the 65 kDa antigen. These results indicate compartmentalization of the immune response to the 65 kDa antigen and, in addition, provide evidence for in vivo involvement of this antigen in the immune response to M. tuberculosis.