Abstract
SUMMARYThe ability of mouse alloantibody to inhibit EA rosette formation and antibody‐dependent cell‐mediated cytotoxicity (ADCC) was used to study the expression of H‐2K, Ia and H‐2D antigens in various tissues. As previously reported antisera against each of these groups of antigens inhibited B lymphocyte EA rosette formation. Continuing studies confirmed these observations but established that quantitative differences may exist in the ease with which antibody against antigens in each region can inhibit EA rosettes: anti H‐2D and anti‐Ia seemed stronger relative to their cytotoxic titres than anti H‐2K. Possible reasons for this are discussed. When rosette forming cells from other tissues were studied, (bone marrow cells, peritoneal macrophages and tumour cells), they were inhibited by anti H‐2K and anti H‐2D sera but not by anti Ia sera, presumably reflecting the restricted distribution of Ia antigens in those tissues.Inhibition of ADCC by various antisera reflected qualitatively and quantitatively the expression of H‐2 antigens in various tissues: whereas effector cell activity in spleen, bone marrow, or peritoneal cell populations was inhibited by anti H‐2 or anti‐Ia sera, the amount of inhibition observed with anti‐Ia was much less when the tissue expressed little Ia antigen (bone marrow) than when it expressed abundant Ia antigen (spleen). The ability of cytotoxicity inhibition to detect antibody coated cells was used to assess the relative amount of Ia antigen on thymus and on lymph node cells, showing significant amounts of Ia antigen on thymus cells. Fc receptor inhibition studies may thus be useful as new approaches to the study of the expression of the antigens of the major histocompatibility complex.
Highlights
Fc receptors and their relationships with membrane alloantigens are natural sources of interest to the immunogeneticist
Surface antigens to inhibit Fc receptor binding (and the ability of anti-Ia to inhibit binding of aggregated immunoglobulin by the Fc receptor (Dickler & Sachs, 1974)) has greatly stimulated studies in this field
We have been studying the inhibitory action of antibody in each of two Fc receptor dependent assays: (i) EA rosettes, in which Fc receptor bearing cells form rosettes with antibody-coated erythrocytes; (ii) antibody-dependent cellmediated cytotoxicity (ADCC), in which cytotoxic effector cells bearing Fc receptors lyse antibody-coated Wr-labelled target cells
Summary
Fc receptors and their relationships with membrane alloantigens are natural sources of interest to the immunogeneticist. Surface antigens to inhibit Fc receptor binding (and the ability of anti-Ia to inhibit binding of aggregated immunoglobulin by the Fc receptor (Dickler & Sachs, 1974)) has greatly stimulated studies in this field. In addition to providing information about possible antigenic associations of the Fc receptor?such studies can provide methodology to study properties of the cell surface antigens themselves. The present report will show that Fc receptor dependent assays can be used to obtain information about the expression of cell surface antigens in various tissues. In EA rosettes, antibody against antigens on the surface of the rosette forming cell (RFC-in our previous studies usually B lymphocytes) inhibited EA rosette formation (Schirrmacher et al, 1975a; Halloran et al, 1975). Steric hindrance of cell contact was a possible explanation of the inhibition (for discussion see Halloran et al, 1975; Schirrmacher & Halloran, 1975)
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