Receptors for the FC Portion of Immunoglobulins (FCR) on Murine Oral Mucosal T Cells

The incidence and distribution of immunoglobulin receptors on oral mucosal T cells were investigated. Enrichment of either Thy-1.2, L3T4 or Lyt-2.2-positive cells was achieved by the use of a panning procedure following cell extraction by an optimized digestion method that preserved all three T-cell markers. The percentage of cells possessing Fc receptors was determined by using immunoglobulin-coated (IgM, IgG or IgA) fluorescent microspheres in a multipoint rosetting assay. We report that approximately 60% of Thy-1.2, L3T4 and Lyt-2.2 positive cells bear FcyR whereas less than 5% of T cells of any subset bear FcaR or FcjiR. In frozen tissue sections, FcyR+ cells were mainly scattered throughout the basal and suprabasal epithelium and were observed at a lower frequency in the minor salivary gland network. From their distribution, it is anticipated that FcyR+ cells may be involved in the surveillance of the epithelium while the minor FcocR+ L3T4+ T lymphocyte population may promote the expression of slgA by resident slgM-bearing B cells, and their differentiation into IgA plasma cells.