INFLUENCE OF THE MOUSE BCG, TBC-1 AND XID GENES ON RESISTANCE AND IMMUNE-RESPONSES TO TUBERCULOSIS INFECTION AND EFFICACY OF BACILLE CALMETTE-GUERIN (BCG) VACCINATION

We have studied the role of three mouse distinct non-H-2 genes (Beg, T bc-1, rid) in several phenomena of antituberculosis immunity and resis tance. On the basis of median survival time (MST) of mice following in fection with virulent Mycobacterium tuberculosis H37Rv, Beg gene did n ot control resistance to the lethal dose of H37Rv infection in non-vac cinated and Myco. bovis (BCG)-vaccinated mice. However, Bcg(r) allele, in comparison with Bcg(s) allele, determined more effective suppressi on of an early multiplication in spleens of H37Rv mycobacteria after a low dose (5 x 10(4) colony-forming units (CFU)) injection. CBA/N mice , which are not protected efficiently against tuberculous challenge by BCG vaccination, were characterized by a decreased in vitro prolifera tion of immune lymph node cells, both spontaneous and stimulated with mycobacterial antigens. The decreased proliferation was due to immunos uppression caused by interactions between responding T cells and CBA/N antigen-presenting cells (APC). We have confirmed that the defective response to BCG-vaccination in CBA/N mice is linked with the X-chromos ome and thus is presumably determined by the xid gene itself. I/St mic e (Tbc-1(s)), supersusceptible to H37Rv infection, were not able to re strict the growth of H37Rv mycobacteria in spleens, even following inf ection with a low dose (5 x 10(4)), but restricted the growth of Myco. bovis BCG more effectively than Bcg(s) mice.