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Identification of prohibitin as a target of IVIg on human B cells
Author(s) -
Proulx Dominic Paquin,
Aubin Éric,
Lemieux Réal,
Bazin Renée
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.1074.34
Subject(s) - prohibitin , immunoprecipitation , antibody , cell , biology , microbiology and biotechnology , phosphorylation , chemistry , immunology , biochemistry , mitochondrion
IVIg are therapeutic preparations of human IgG prepared from the plasma of thousands of donors and are currently used to treat more than one hundred autoimmune or inflammatory diseases, although their mechanism of action is not precisely known in any of these diseases. Previous work from our laboratory showed that IVIg could directly influence the fate of human B cells by inducing their differentiation (Blood, 2003; 101:3065). The goal of the present study was to identify the membrane target of IVIg on human B cells. We used two different methods to isolate the B cell membrane proteins recognized by IVIg (classical immunoprecipitation following incubation with IVIg and cell solubilization, and affinity chromatography of soluble membrane proteins on IVIg‐Sepharose). The recovered proteins were identified by LC‐MS. Surprisingly, most of them were not membrane receptors but intracellular proteins such as actin, prohibitin 1 and 2, heat shock cognate 71KDa protein and RPL13. Since prohibitin is known to be associated with the BCR, at least in IgM‐expressing B cells (EMBO J, 1994; 13:3782), and to regulate events such as ERK phosphorylation and progression in the cell cycle, we have examined more closely the association between IVIg, BCR and prohibitin. Preliminary results suggest that IVIg interact with prohibitin in a BCR‐independent way. The role of prohibitin in the effects of IVIg on human B cells is currently under study.