title: Characterization of human T cell-derived IgE-potentiating factor.
abstract: We have previously shown that Fc epsilon receptor-positive (Fc epsilon R+) T cell lines from patients with the hyper IgE syndrome secrete IgE-binding factors which selectively enhance IgE but not IgG synthesis in cultures of B cells obtained from patients with allergic rhinitis but not from nonatopic subject. In the present study we have tested the effect of supernatants from Fc epsilon R+ T cell lines on a large panel of B cells from atopic patients (n = 20). We found that IgE synthesis was selectively enhanced only in B cell cultures in which there was ongoing spontaneous synthesis of IgE. The target of IgE-potentiating factor(s) was a large low-density B cell present in the circulation of responding atopic donors. In addition, we further characterized IgE-potentiating factors derived from Fc epsilon R+ T cell lines. The factor(s) fractionated into 2 peaks on Sephadex G-75 with approximate molecular masses of 15,000 and 60,000 kDa, and had affinity for lentil lectin but not for peanut agglutinin. Release of IgE-potentiating factor(s) was enhanced by the addition of exogenous human IgE to Fc epsilon R+ T cell cultures and was inhibited by tunicamycin, an inhibitor of N-glycosylation. These studies suggest a close homology between the physicochemical characteristics of human and rodent IgE-potentiating factors and the immune signals which modulate production of these IgE regulatory factors.
mesh_terms: D001402:B-Lymphocytes / Q000276:immunology; D002460:Cell Line; D006801:Humans; D007073:Immunoglobulin E / Q000096:biosynthesis; D008222:Lymphokines / Q000276:immunology*; D029584:Prostatic Secretory Proteins; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D008222:Lymphokines; D029584:Prostatic Secretory Proteins; C043076:beta-microseminoprotein; C013059:immunoglobulin-binding factors; D007073:Immunoglobulin E