Differential glycosylation of two glycoproteins synthesized by murine B cells in response to IL-4 plus IL-5

We sought to determine whether selected cytokines, known to stimulate profo undly B-cell activation and differentiation, also have as yet unrecognized effects upon the glycosylation of secreted Ig and/or membrane-associated pr oteins. The glycosylation of both secreted IgM and membrane-bound MHC Class -I synthesized by CH12LX cells was detected by enzyme-lectin conjugates in immunoabsorption assays. Stimulation of B cells with IL-4 plus IL-5 signifi cantly decreases the terminal glycosylation of secreted IgM, whereas LPS ha s a minor effect, despite the fact that both stimuli are equipotent for IgM secretion, Neither LPS nor IL-4 plus IL-5 affect MHC Class-I expression. H owever, IL-4 plus IL-5 substantially increases the terminal glycosylation o f MHC Class-I produced from both mIgM(+) and mIgA(+) CH12LX cells, LPS has no or a modest effect on the terminal glycosylation of MHC Class-I produced from CH12LX cells. These results suggest that Th-2-derived cytokines diffe rentially influence the glycosylation of secreted and membrane-associated g lycoproteins of B cells. In turn, this might elucidate the basis of aberran t glycosylation reported in conditions such as IgA nephropathy, cancer and rheumatoid arthritis. (C) 2000 Academic Press.