CONTRIBUTION OF ALPHA/BETA AND GAMMA/DELTA T-LYMPHOCYTES TO IMMUNITY AGAINST MYCOBACTERIUM-BOVIS BACILLUS-CALMETTE-GUERIN - STUDIES WITH T-CELL RECEPTOR-DEFICIENT MUTANT MICE

Mutant mice with defined T cell deficiencies were infected with Mycobacterium bovis bacillus Calmette Guerin (BCG) and the relative contribution of alpha/beta T cells and gamma/delta> T cells to the host immune response was assessed. Recombinase activating gene (RAG-1)(-/-) mutants as well as T cell receptor (TcR) beta(-/-), but not TcR-delta(-/-), mutants succumbed to M. bovis BCG infection and failed to develop granulomatous lesions. Antigen-induced IFN-gamma production by spleen cells in vitro was abrogated in RAG-1(-/-) mutants and markedly diminished in TcR-beta(-/-) and TcR-delta(-/-) mice. Reconstitution experiments suggest that both alpha/beta and gamma/delta T cells are essential for antigen-specific IFN-gamma secretion. Our data formally prove the crucial role of alpha/beta T cells and reveal accessory functions of gamma/delta T cells in optimum immunity against M. bovis BCG.