Poly[N-acetyl-lactosamine]-type sugar chains in CD45 antigens of abnormal T cells of lpr mice are different from those of normal T cells and B cells.

The lymph node (LN) T cells from autoimmune MRL/MpJ-lpr/lpr (lpr) mice and control MRL/MpJ-+/+ (+/+) mice were compared as to their cell surface lectin binding sites and the glycoproteins responsible for the lectin binding. T cells from enlarged lymph nodes of lpr mice were found to express more binding sites for lectins which are reactive to poly[N-acetyl-lactosamine]-type sugar chains than normal +/+ mouse lymph node T cells. Furthermore, we found that high mol. wt (180,000-220,000) glycoproteins on lpr T cells were strongly stained with these poly [N-acetyl-lactosamine]-binding lectins on Western-blotting. These glycoproteins were found to belong to the CD45 family on immunoprecipitation and absorption with monoclonal anti-CD45 antibody. Thus, aberrant expression of high mol. wt CD45 (CD45R) antigens on lpr T cells may contribute greatly to the strong reaction of these cells with poly[N-acetyl-lactosamine]-binding lectins. We also found that poly[N-acetyl-lactosamine]-type sugar chains are more abundant on B cells than on lpr T cells, and that the molecular weights and the carbohydrate moieties of CD45R antigens on lpr T cells are different from those of CD45R antigens on +/+ spleen B cells.