Relationship of B cell Fc receptors to T cell recognition of Mls antigen.
The Mls locus on chromosome 1 controls the expression of cellular determinants that are responsible for stimulating mixed lymphocyte reactions between H-2-identical strains. However, the biochemical nature of Mls antigenic determinants remains undefined. It has been proposed that Ly-17 lymphoid cell surface antigens (also known as Ly.m.20.2 and LyM-1) and Mls antigens could be identical because they are both encoded by loci on chromosome 1 and display similar tissue distribution. The Ly-17 locus encodes polymorphic alleles of the IgG Fc receptor (Fc gamma R). In the present study, two approaches were used to address the question of whether Fc gamma R are involved in T cell recognition of Mls antigen. In the first approach we tested the effect of Fc gamma R blockade by heat-aggregated mouse IgG or anti-Fc gamma R monoclonal antibodies (2.4.G2) on the ability of an Ia+, Fc gamma R+ Mlsa-expressing B cell hybrid (LBB.3.4.16) to stimulate interleukin 2 secretion by an anti-Mlsa-specific T cell hybrid. We show that blockade of Fc gamma R does not inhibit the Mlsa-specific stimulation of T cells during a 24-h culture period in which Fc gamma R remain blocked. In the second approach, we derived irradiation-induced variants of LBB.3.4.16 to dissociate Fc gamma R expression and Mls antigen expression. We describe 2 LBB variants which no longer stimulate Mlsa-reactive T cells but do express Fc gamma R. Compared to parental LBB cells, the capacity of variant LBB cells to present soluble antigen to Ia-restricted T cells is unaffected. Collectively, these results indicate that Fc gamma R expression and Mlsa antigen stimulation can be dissociated. We conclude that Fc gamma R expression may be necessary, but not sufficient for T cell recognition of Mls antigen.
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D000954:Antigens, Surface / Q000276:immunology*; D001402:B-Lymphocytes / Q000276:immunology*; D006822:Hybrid Cells / Q000276:immunology; D007074:Immunoglobulin G / Q000276:immunology; D007959:Lymphocyte Culture Test, Mixed; D051379:Mice; D011961:Receptors, Fc / Q000276:immunology*; D017452:Receptors, IgG; D012397:Rosette Formation; D013601:T-Lymphocytes / Q000276:immunology*
D000911:Antibodies, Monoclonal; D000954:Antigens, Surface; D007074:Immunoglobulin G; D011961:Receptors, Fc; D017452:Receptors, IgG