Receptors for the F_CPortion of Immunoglobulins (F_CR) on Murine Oral Mucosal T Cells

Abstract

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 Fc gamma R whereas less than 5% of T cells of any subset bear Fc alpha R or Fc mu R. In frozen tissue sections, Fc gamma R+ 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 Fc gamma R+ cells may be involved in the surveillance of the epithelium while the minor Fc alpha R+ L3T4+ T lymphocyte population may promote the expression of sIgA by resident sIgM-bearing B cells, and their differentiation into IgA plasma cells.