Identification of a Sulfate-Bearing Molecule Associated with HLA Class II Antigens

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 81; no. 5; pp. 1534 - 1538
• Main Authors: Sant, Andrea J., Cullen, Susan E., Schwartz, Benjamin D.
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences of the United States of America 01.03.1984; National Acad Sciences
• Subjects: Adolescent; B lymphocytes; Cell Line; Cell lines; Chromosomes, Human, 6-12 and X; Electrophoresis, Polyacrylamide Gel; Gels; Genes, MHC Class II; Glycoproteins; Histocompatibility Antigens Class II - analysis; HLA antigens; Humans; Leucine - metabolism; Lymphocytes - immunology; Macromolecular Substances; Major Histocompatibility Complex; Male; Materials; Molecular Weight; Molecules; Palatine Tonsil - immunology; Palatine tonsils; Proteoglycans; Sulfates; Sulfates - metabolism; Sulfur Radioisotopes; Tritium
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.81.5.1534

The human Ia antigens (DR, DS, and SB), determined by genes contained within the HLA complex on chromosome 6, are glycoprotein heterodimers consisting of a Mr≈ 34,000 α chain and a Mr≈ 28,000 β chain. As a result of studies exploring the possibility that α or β (or both) might be sulfated, a unique component of the oligomeric Ia antigen complex was discovered. When anti-Ia immunoprecipitates from Nonidet P-40 lysates of [35S]sulfate-labeled lymphoid cells were analyzed by NaDodSO4/PAGE, a molecule of considerable size heterogeneity (Mr40,000-70,000) was observed. This component was present in both anti-DR and anti-DS immunoprecipitates prepared from both human tonsil cells and lymphoblastoid B-cell lines but was not observed in control precipitates or in association with immunoglobulin or class I HLA molecules. Preliminary biochemical studies indicate that this Mr40,000-70,000 molecule is polyanionic, disperse in molecular weight, and sensitive to protease digestion. The sulfate-bearing moiety of this component was resistant to Pronase but sensitive to chondroitinase ABC, indicating that this molecule belongs to the chondroitin sulfate class of proteoglycans.