Tissue distribution and cytofluorometric analysis of oral mucosal T cells in the BALB/c mouse

The incidence and distribution of Thy-1.2+, Lyt-2.2+ and L3T4+ cells in the murine oral mucosa were investigated using qualitative and quantitative approaches. From immunostaining of frozen tissue sections, it appeared that the majority of oral T cells are located either in the epithelium or within the minor salivary gland network. The occurrence of Thy-1.2+, L3T4+ and Lyt-2.2+ cells at these sites points to two strategic lines of defence in the event of mucosal infections or aggression. A quantitative analysis of oral T-cell subsets was made possible by optimizing an enzymatic digestion procedure which preserves all three T-cell surface markers. Flow cytometric analysis of oral mucosal cells demonstrated that the helper phenotype is about twice as numerous as the cytotoxic/suppressor phenotype in the mucosa. Furthermore, in single cell suspensions, virtually all Thy-1+ cells were either L3T4+ or Lyt-2.2+ in the mucosa and in the spleen. From this frequency analysis and our previous studies, we conclude that T cells are a major component of the oral immune system, being 2-3 times as numerous as B cells or macrophages. Present data on the spatial distribution and characteristic ratio of T-cell subsets assess the basal activity of the local T-cell populations in healthy animals and lay the basis for comparative studies of both qualitative and quantitative variations occurring during mucosal infections or autoimmune reactions.