The phenotypes of lymphocytes in the large intestinal patches (LIP) of lambs were examined by flow cytometry and immunohistology, using a panel of monoclonal antibodies (mAb), and compared to those found in the jejunal (JPP) and ileal Peyer's patches (IPP). T-cell markers were detected on 25% of the LIP and JPP lymphocytes by cytofluorometry, and nearly all T cells expressed the CD4 molecule. In contrast, T cells were scarce in the IPP (less than 1%). The B-cell marker p220 was expressed by 74% of the LIP lymphocytes, whereas surface immunoglobulin-positive cells comprised 50-60% of the lymphocyte population. The adhesion molecule CD2 was expressed by a larger proportion of cells from the LIP and JPP than from the IPP, whereas the adhesion molecule CD44 was detected on more IPP lymphocytes. Major histocompatibility complex (MHC) class I antigens were expressed by nearly all lymphocytes from the LIP, JPP and IPP. The LIP contained 70-80% cells with MHC class II expression, whereas the majority of IPP cells (greater than 95%) were MHC class II positive. Immunohistology showed many CD4+ T lymphocytes in the follicles of the LIP and JPP, but none in the IPP follicles. CD8+ lymphocytes were found in the interfollicular areas and were absent from the follicles. The interfollicular areas of the rectal patch contained about 15% tau delta T cells. In contrast, the JPP, IPP and the colon patch at the beginning of spiral colon contained less than 3% tau delta T cells.
Animals Antigens, Surface