The response of gut-associated T lymphocytes to intestinal viral immunization

The cell-mediated immune response by the gut-associated lymphoid tissues to antigen within the intestinal tract is poorly understood. Our objective was to investigate the antigen-specific T cell proliferative response and cytotoxic T lymphocyte (CTL) response of cells from the GALT after enteric immunization with vaccinia virus. Lymphocytes able to proliferate in the presence of vaccina virus in vitro were found in large numbers in mesenteric lymph nodes (MLN) 6 days after the injection of vaccinia virus into the lumen of the small bowel. The MLN at this time also contained vaccinia-specific CTL, but unlike the proliferating cells, which were found for several weeks after immunization, the CTL were demonstrable in the MLN for only a few days. Peyer's patches were found to contain neither antigen-stimulated proliferating cells nor CTL. The viral-specific proliferating lymphocytes from the MLN 10 days after immunization were sIg^-, monoclonal antibody W3/25⁺, MRC OX-8^- large lymphoblasts. The vaccinia-specific CTL were also large lymphoblasts, but they belonged to the W3/25^-, OX-8⁺ subset. Thus, a strong T helper and cytotoxic T lymphoblast response is generated within the MLN after viral challenge of the gut.