IgE synthesis by chronic lymphocytic leukemia cells.
The present results indicate that B cells isolated from chronic lymphocytic leukemia (B-CLL) from 11 of 14 patients are capable of specifically producing IgE upon costimulation with IL-4 and hydrocortisone (HC). IgE is detected by intracytoplasmic fluorescence staining and by RIA. Clinical, hematological, and immunological parameters (including Rai stage, WBC, Lc, sIg kappa/lambda, CD5, and CD23 expression) cannot distinguish the IgE responder from the nonresponder patients. IL-4 alone is a potent inducer of human IgE synthesis by normal PBMC and we show here that its effect is strikingly enhanced by HC. The IgE produced by B-CLLs are monoclonal since they display the same L chain type as the freshly isolated CD5+ B-CLLs. We, therefore, conclude that the combination of IL-4 and HC can abrogate the maturation arrest of CD5+ B-CLLs by inducing their differentiation into IgE-producing cells. The present data provide a unique model to study the isotype switching to IgE and the regulation of human IgE synthesis by monoclonal human B cells.
Sarfati
M
M
Notre-Dame Hospital Research Centre, University of Montreal, Quebec, Canada.
Luo
H
H
Delespesse
G
G
D000943:Antigens, Differentiation; D018956:CD5 Antigens; D002454:Cell Differentiation / Q000187:drug effects; D006801:Humans; D006854:Hydrocortisone / Q000494:pharmacology; D007073:Immunoglobulin E / Q000096:biosynthesis*; D066298:In Vitro Techniques; D015847:Interleukin-4 / Q000494:pharmacology; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D014407:Tumor Cells, Cultured
D000943:Antigens, Differentiation; D018956:CD5 Antigens; D015847:Interleukin-4; D007073:Immunoglobulin E; D006854:Hydrocortisone