Résumé : A 32-kilodalton protein antigen (P32) was previously purified to homogeneity from culture filtrate of Mycobacterium bovis BCG (J. De Bruyn, K. Huygen, R. Bosmans, M. Fauville, R. Lippens, J. P. Van Vooren, P. Falmagne, H. G. Wiker, M. Harboe, and M. Turneer, Microb. Pathog. 2:351-366, 1987). Spleen cells from BCG-sensitized mice produce significant amounts of gamma interferon (IFN-gamma) in response to this P32 protein. The amount of secreted IFN-gamma is influenced by mouse genotype, with C57BL/6 (H-2b), C57BL/10 (H-2b), and 129/Sv (H-2b) mice producing about four times more than BALB/c (H-2d), CBF1 (H-2d/b), and DBA/2 (H-2d) mice do. Analysis of seven recombinant inbred strains derived from the BALB/c x C57BL/6 cross and of congenic mice differing in major histocompatibility complex-coding chromosome 17 fragments indicates a probable H-2-linked control of this IFN-gamma induction, with H-2b cells producing high titers and H-2d cells producing low titers in response to the P32 antigen.