Expression of the sialosyl-Tn epitope on CD45 derived from activated peripheral blood T cells.
The cell surface protein tyrosine phosphatase CD45 is a major target of IgM anti-T cell autoantibodies in systemic lupus erythematosus (SLE). The autoreactive determinants on CD45 are O-linked glycans expressed on activated T cells and certain T cell lines, rather than linear or conformational polypeptide epitopes or N-linked glycans. To identify oligosaccharide structures that may play a role in the functional interactions of CD45 or are candidate target epitopes of SLE anti-CD45 autoantibodies, autoreactive CD45 purified from Jurkat T cells and non-autoreactive CD45 purified from CLL B cells were tested by ELISA for expression of mucin-type O-glycan structures. Monoclonal antibodies (mAbs) directed against blood group A, type 1 H chains, type 2 H chains, T, Le(a), sialylated-Le(a), Le(b), sialylated-Le(c), Le(x), sialylated-Le(x), multi-fucosylated Le(x), Le(y), and sialylated-extended Le(v) failed to react with CD45 from either B cells or T cells. However, mAbs directed against Tn (galNAcalpha1-->O-ser/thr) or sialosyl-Tn (neuNAcalpha2-6gaINAcalpha1-->O-ser/thr) structures reacted with CD45 derived from Jurkat T cells, but not from CLL B cells. Anti-Tn mAbs also reacted in western blotting procedures with CD45 isolated from Jurkat T cells, but did not react with CD45 isolated from CEM, MOLT-3, or PEER T cells; Daudi, Raji, or CLL B cells; or resting or Con A-activated PBL. However, anti-sialosyl-Tn mAbs stained blots of CD45 isolated from Jurkat and CEM T cells and Con A-activated PBL, a pattern of reactivity similar to that of the anti-CD45 autoantibodies. Flow cytometric analyses demonstrated that the sialosyl-Tn epitopes are expressed on a subpopulation of CD4 +/CD8- T cells.
Fernsten
P
P
Division of Rheumatology and Immunology, Thurston Arthritis Research Center, The University of North Carolina at Chapel Hill, 27599, USA.
Shaw
M
M
Hocker
S
S
Fulghum
R
R
Winfield
J
J
D000911:Antibodies, Monoclonal; D001323:Autoantibodies / Q000097:blood; D001402:B-Lymphocytes / Q000276:immunology; D002241:Carbohydrates / Q000737:chemistry; D002460:Cell Line; D003208:Concanavalin A / Q000494:pharmacology; D000939:Epitopes / Q000737:chemistry; D006801:Humans; D007075:Immunoglobulin M / Q000097:blood; D066298:In Vitro Techniques; D019169:Jurkat Cells; D017493:Leukocyte Common Antigens / Q000737:chemistry*; D008180:Lupus Erythematosus, Systemic / Q000276:immunology; D008213:Lymphocyte Activation; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1; D012794:Sialic Acids / Q000737:chemistry; D016176:T-Lymphocyte Subsets / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology*
D000911:Antibodies, Monoclonal; D001323:Autoantibodies; D002241:Carbohydrates; D000939:Epitopes; D007075:Immunoglobulin M; D012794:Sialic Acids; D003208:Concanavalin A; D017493:Leukocyte Common Antigens; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1