Fc IgM receptors on human lymphoblastoid B cell lines

✍ Scribed by W. J. Pichler; S. Broder; Linda Muul; I. Magrath; T. A. Waldmann

• Publisher: John Wiley and Sons
• Year: 1978
• Tongue: English
• Weight: 512 KB
• Volume: 8
• Category: Article
• ISSN: 0014-2980
• DOI: 10.1002/eji.1830080411

✦ Synopsis

Five human lymphoblastoid cell lines have been investigated for their ability to secrete immunoglobulins (IgG, IgA, IgM) and for the presence of different cell surface markers, with special emphasis on the F c IgM receptor, using a rosette technique with IgM-coated bovine red blood cells (EA-IgM).

Four cell lines (Hu, 8432, SB, PA3) were characterized as having a B cell origin due t o the presence of surface immunoglobulins, complement receptors, mouse red blood cell rosette formation, low avidity F c IgG receptors and absence of sheep red blood cell rosette formation. Two of these B cell lines (Hu and PA3) secreted IgM, two cell lines (8432 and SB) secreted IgG, while the human T cell line Molt 4 did not secrete Ig.

All four B cell lines exhibited F c IgM receptors (17-35 %) while the T cell line Molt 4 had no detectable F c IgM receptor. The receptor was specific for IgM. Neither aggregated IgG, soluble IgG immune complexes nor EDTA could abrogate the rosette formation. IgM immune complexes, pure human IgM, as well as normal human serum had an inhibitory effect on EA-IgM rosette formation. The receptor was trypsin-sensitive and required protein synthesis for expression.

There was n o correlation between the expression of F c IgM receptors and secretion of any given Ig class, indicating that B cells may express Fc IgM receptors independently of their commitment t o produce IgM or IgG.