New aspects of FcγRII-mediated regulation of human B cells

J. Gergely, Z. Rozsnyay, G. Sármay

Research output: Contribution to journalArticle

Abstract

Both the membrane-bound type II Fcγ receptor (FcγRII) expressed on B lymphocytes and soluble FcγRII (sFcγRII) released from the cells are involved in the regulation of B-cell response. The crosslinking of FcγRII and antigen receptor (BCR) results in a negative signal for the antibody production. Soluble FcRs modulate the in vitro synthesis of immunoglobulins and regulate antibody production in an isotype-specific manner. Studying the mechanism of FcγRII-mediated regulation of antibody production we found a correlation between B-cell activation, FcγRII expression, and release of sFcγRII. We have shown that crosslinking of BCR induced Ser phosphorylation of FcγRII, moreover that protein kinases involved in B-cell activation, such as protein tyrosine kinase, fyn, and the Ser/Thr kinase PKC(ε), are associated with FcγRII. It was also demonstrated that activated, but not resting B cells release FcγRII and that the capacity of activated B lymphocytes to shed their receptors correlates with the appearance of a trypsinlike serine protease activity on the cells. Using reverse transcriptase and polymerase chain reaction of tuRNS obtained from resting and activated human tonsil B lymphocytes we have shown that mRNA species of both isoforms are present in the resting cells, although the level of FcγRIIb2 exceeds that of FcγRIIb1. Activation of B cells resulted in the induction of FcγRIIb1, and down-regulation of FcγRIIb2 mRNA splicing. Crosslinking of FcγRII on resting but not the activated B cells inhibited anti-IgM-induced cell proliferation, suggesting that FcγRIlb2, present in higher amount on resting cells, is responsible for this function. As a result of B-cell activation FcγRII is phosphorylated, membrane-bound serine esterases are activated, and due to proteolytic cleavage truncated, (most probably FcγIIb1 type) receptors are released.

Original languageEnglish
Pages (from-to)437-444
Number of pages8
JournalRegional Immunology
Volume6
Issue number5-6
Publication statusPublished - 1995

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B-Lymphocytes
Antibody Formation
Messenger RNA
Antigen Receptors
Membranes
Fc Receptors
Palatine Tonsil
Reverse Transcriptase Polymerase Chain Reaction
Protein-Tyrosine Kinases
Protein Kinases
Immunoglobulins
Protein Isoforms
Phosphotransferases
Down-Regulation
Phosphorylation
Cell Proliferation

ASJC Scopus subject areas

  • Immunology

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New aspects of FcγRII-mediated regulation of human B cells. / Gergely, J.; Rozsnyay, Z.; Sármay, G.

In: Regional Immunology, Vol. 6, No. 5-6, 1995, p. 437-444.

Research output: Contribution to journalArticle

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