LYMPHOCYTE SUBPOPULATIONS IN JEJUNAL AND ILEAL PEYERS-PATCHES OF CALVES WITH EXPERIMENTAL SALMONELLA-DUBLIN INFECTION

Changes of lymphocyte subpopulations in jejunal and ileal Peyer's patc hes (JPP and IPP) of six calves inoculated with Salmonella dublin were investigated at 9 hours, 1, 2, 3 and 7 days post inoculation (p.i.) u sing immunohistochemistry. Reactive areas and area percentages of B-ly mphocytes, as well as CD4+, CD8+ and gammadeltaT-lymphocytes within th e different compartments of PP were estimated using computer-assisted morphometric analysis. A significant, linear decline of the areas of l ymphoid follicles and domes in JPP and IPP due to depletion of B-lymph ocytes was found. The rate of decline was similar in JPP and IPP, but more severe in lymphoid follicles than in domes. Intraepithelial cells in follicle-associated epithelium changed from predominantly B-lympho cytes in controls to CD8+ T-lymphoytes in inoculated calves and cluste rs of B-lymphocytes were observed above domes at days 1 and 2 p.i. Are as of CD4+ and CD8+ T-lymphocytes within lymphoid follicles and domes were increased at 3 and 7 days p.i. resulting in decreased compartment alization of the normally segregated T- and B-lymphocyte populations. The increase of CD4+ and CD8+ T-lymphocytes was, however, significant in lymphoid follicles in the JPP only. No significant changes in the a mount and distribution of gammadeltaT-lymphocytes were observed.