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Proteolysis Increases the Fc‐Mediated Binding of Murine IgG2b to Human EBV‐Transformed B Cells, but Decreases the Expression of FcγRII and FcγRII
Author(s) -
HOLTROP S.,
RIJKESCHILDER G. P. M.,
DOORN N. E. M.,
JACOBS C. W. M.,
KOENE R. A. P.,
TAX W. J. M.
Publication year - 1993
Publication title -
scandinavian journal of immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.934
H-Index - 88
eISSN - 1365-3083
pISSN - 0300-9475
DOI - 10.1111/j.1365-3083.1993.tb01723.x
Subject(s) - cathepsin g , pronase , proteolysis , microbiology and biotechnology , receptor , elastase , epstein–barr virus , biology , cathepsin b , chemistry , enzyme , immunology , virus , trypsin , biochemistry
We have previously described a polymorphic human Fc receptor for murine IgG2b (mIgG2b). This receptor was defined by the binding of (complexed) mIgG2b to monocyles and Epstein‐Barr virus (EBV)‐transformed B cells. Three per cent of normal individuals were high responders with respect to mIgG2b (mIgG2b‐HR), whereas the other individuals were low responders for mIgG2b (mlgG2b‐LR). In the present study we investigated the effect of proteolytic enzymes on the Fc‐mediated binding of mIgG2b to EBV‐B cells. Pronase, human leucocyte elastase and cathepsin G caused an inereased binding (in an EA‐rosetting assay) of mIgG2b to EBV‐B cells from mIgG2b‐HR, but not from mIgG2b‐LR. Simultaneous immunofluorescence studies demonstrated that these protcolytic enzymes strongly reduced the expression of FcγRII and FcγRII on these cells, whereas HLA class I or HLA class II molecules were not affected. These findings strongly suggest that binding of mIgG2b is not mediated by FcγRII or FcγRII We also studied the effect of proteolysis on mIgG2b‐HR EBV‐B cells from an HLA class II‐negative individual. In this case EA‐mIgG2b rosetting was decreased after proteolysis, suggesting that HLA class II molecules may have a role in protecting the binding site for mIgG2b against proteolytic destruction.