PRESENCE OF ANTIGENIC DETERMINANTS COMMON TO FC-IGE RECEPTORS ON HUMAN MACROPHAGES, LYMPHOCYTE-T AND LYMPHOCYTE-B AND IGE-BINDING FACTORS

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  • 1 December 1986
    • journal article
    • research article
    • Vol. 59  (4) , 569-575
Abstract
The present study indicates that two Mab specific to Fc.epsilon.R (MAbER) on human B lymphocytes also react with Fc.epsilon.R on macrophage and T-cell lines. More importantly, it is also shown that MabER cross-react with IgE-BFs derived from B, T and macrophages cell lines. This conclusion is supported by the following observations: (i) the binding of MabER to Fc.epsilon.R-bearing cells is blocked by the CSN of T, B and macrophage Rc.epsilon.R-bearing cell lines, known to contain IgE-BFs as shown by their inhibition of rosette formation between IgE-coated erythrocytes and Fc.epsilon.R-bearing cells; (ii) the material purified from the CSN of each Fc.epsilon.R(+) cell lines by affinity chromatography on MabER-Affi-gel blocks the rosetting of U937 cells with IgE but not with IgG-coated erythrocytes; (iii) the same affinity-purified material inhibits the binding of 125I-IgE to a selected anti-IgE Mab (Mab 75); and (iv) the CSN of Fc.epsilon.R(+) cells but not of Fc.epsilon.R(-) cells reacts in a solid-phase sandwich radioimmunoassay with two MabER (135-176), and their reactivity is significantly retained on IgE-Affi-gel from which it may be recovered by glycine elution. The RIA is not influenced by any class of Ig, including IgE, employed at a final concentration of 100 .mu.g/ml. Human serum also reacts in the RIA, and parallel dilution curves are obtained with different CSN and human sera. The RIA proved to be a reproducible and sensitive method to quantify human IgE-BFs. The expression of the same antigenic determinants on Fc.epsilon.R from T, B and macrophages as well as on the IgE-BFs secreted by these cells indicates structural homology between IgE receptors and IgE-FBs and suggests that they are encoded by the same gene.