Lymphocytes Bearing Fc Receptors for IgE

Abstract

Abstract Human peripheral blood lymphocytes from ragweed-sensitive individuals were fractionated by a rosette technique with neuraminidase-treated sheep erythrocytes (En). A significant number of FcεR-bearing cells were detected in the T cell fraction by rosette formation with ox erythrocytes coated with human IgE (E'-hIgE), or by the binding of fluoresceinated F(ab′)2 fragments of anti-IgE complexed with IgE. The majority of these lymphocytes in the T cell fraction formed mixed rosettes with En and E'-hIgE. T cells bearing FcεR were demonstrated in the mesenteric lymph node cells from rats infected with Nippostrongylus brasiliensis (Nb); about 3% of the total cells in a B-depleted fraction formed rosettes with ox erythrocytes coated with rat IgE (E'-rIgE). Most of the rosette-forming cells (RFC) in the fraction were stained by antibodies specific for rat T cells in immunofluorescence. A substantial proportion (5 to 10%) of lymphocytes in rat-activated T cells, which were prepared by transfer of Lewis strain thymocytes to Sprague-Dawley rats, formed rosettes with E'-rIgE, and essentially all of the RFC were stained by anti-T cell antibodies. The results indicated that a subset of human and rat T cells possess FcεR. Evidence was obtained that FcεR on T cells are distinct from Fc receptors for IgG (FcγR), which were demonstrated by rosette formation with ox erythrocytes coated with rabbit IgG antibodies (EA). Mixed rosette assays showed that more than a half of FcεR-bearing human T cells failed to bind EA. Similarly, the majority of FcεR-bearing T cells in the lymph nodes of Nb-infected rats failed to bind EA. In activated T cell preparations, however, about three-fourths of FcεR-bearing cells formed mixed rosettes with EA, indicating that some T cells bear both FcεR and FcγR.