C3b acceptors (C3bAs) of human peripheral blood mononuclear cells (PBMC) reacting with the labile binding site of nascent C3b (C3b(x)) have been investigated by the immune adherence (IA) test. In non-cellular systems some conventional chemical groups (OH-, NH2-) have been reported to be the target of the covalent binding of C3b(x). Thus it should be assumed that every cell can fix C3b(x) via its labile binding site and C3bAs are barely saturable. Contrary to this expectation, however, normal human PBMC were found to be heterogeneous from this point of view, as 57 ± 4% of B cells and 21 ± 2% of Null cells possess C3bAs while T cells do not. C3bAs of human PBMC are saturable and trypsin-sensitive structures. The covalent nature of the C3b(x)-C3bA interaction has also been proved. Studying the effect of acceptor-bound C3b on the function of other cell-surface structures, the inhibition of the Fcγ receptor function and the abolishment of the enhancement of pokeweed mitogen-stimulated blastogenesis by immune complexes were found.
|Number of pages||8|
|Publication status||Published - aug. 11 1983|
ASJC Scopus subject areas
- Immunology and Allergy