B-cell-mediated depression of the granulomatous response to BCG in mice

The depression of the granulomatous response to Mycobacterium bovis strain BCG in mice infected intravenously with 2 x 10(7) CFU of the microorganism turned out to be mediated by various types of cells arising at different times after infection. Anti-PPD B lymphocytes were found to play a major role at Day 1 after infection and to be no longer effective 4 days later. At this time the depression was mediated by anti-idiotype B lymphocytes, whereas T lymphocytes proved to be involved in later phases of the infectious process. These results show that B lymphocytes may be of critical importance in the regulation of cell-mediated immune reactions to this facultative intracellular parasite.