Phenotypic and functional analysis of mucosal lymph node T cell subpopulations proximal and distal to chronic staphylococcal antigen challenge.

We investigated the functional and subset surface marker characteristics of supramammary lymph node T cell populations at sites proximal and distal to the mammary region of goats repeatedly injected with heat-treated Staphylococcus aureus antigen (HK-SAC). Flow cytometric studies showed quantitative differences in CD4+ and CD8+ T cell subsets among large and small lymphocyte populations in ipsilateral and contralateral supramammary lymph nodes of these animals. Although ipsilateral (draining) lymph nodes were enriched with CD4+ and CD8+ T cells, CD4/CD8 ratios were comparatively lower than those of contralateral (non-draining) lymph nodes (2.30 vs 2.60, respectively). Cell size analysis by flow cytometry showed that nearly 70% of the lymphocytes in ipsilateral nodes were of large cell phenotype with CD4/CD8 ratios of 2.52. In contrast, there were only 56.1% large lymphocytes in contralateral lymph nodes but with similar CD4/CD8 ratios of 2.55. The number of large lymphocytes in corresponding nodes of uninoculated control animals was significantly lower (50%) with much lower CD4/CD8 ratios (2.08). Alloantigenic responses of both ipsilateral and contralateral lymph node T cells were greater than those of uninoculated controls. Antigen-specific proliferation studies showed that ipsilateral lymph node T cells greatly enhanced both primed and non-primed lymph node B cell responses to HK-SAC, whereas those from contralateral lymph nodes were less stimulatory. In contrast, contralateral lymph node T cells had greater enhancing effects on PWM-induced polyclonal B cell responses. These studies indicate that repeated local infection with bacterial antigen induce changes in the numbers, ratios and antigen-specific and non-specific responses among ipsilateral (draining) and distal contralateral (non-draining) lymph node T cell populations in mucosal-associated immune systems such as the mammary gland.