Adoptive immunity to Mycobacterium bovis strain bacillus Calmette-Guérin by long-term cultured T-cell line in nude mice.

Tuberculin-active peptide-reactive T-cell lines were established from the popliteal lymph node of BALB/cA mice immunized with heat-killed Mycobacterium tuberculosis to investigate the cellular mechanisms in the protective immunity of tuberculosis. These T-cell lines, consisting mainly of L3T4 surface antigen-positive cells, were transferred intravenously into nude mice infected with M. bovis strain bacillus Calmette-Guérin (BCG). Four or 6 weeks after transfer, footpad swelling and hepatic granuloma formation were observed and viable counts in the liver were decreased. Reduction of viable counts in the liver was obviously preceded by the hepatic granuloma formation. An effect of Lyt-2+ T cells which might be included in the inoculum could be ruled out by the experiment using T-cell lines pretreated with anti-Lyt-2 monoclonal antibody and complement. These results indicated that T cells required for protective immunity in these experiments belong to the L3T4-positive TDTH subset. However, their protective activity was inferior to that of freshly prepared immune lymph node T cells. From the observation of migration patterns of 51Cr-labelled T cells in BCG-infected nude mice, a relatively high proportion of freshly isolated T cells, but only a small part of T-cell line, deposited in the spleen of infected nude mice. This difference in migration pattern of freshly isolated and cultured T cells could be one of the reasons for the less in vivo anti-bacterial activity of the latter.