title: Carbohydrate differences in HLA-DR molecules synthesized by alveolar macrophages and blood monocytes.
abstract: Two-dimensional gel electrophoresis was used to compare immunoprecipitated, radiolabeled HLA-DR molecules synthesized by alveolar macrophages (AM) and blood monocytes (BM) of the same healthy, nonsmoking volunteers. No charge differences were noted by isoelectric focusing. Molecular weight analysis of HLA-DR from AM revealed a complex pattern of radioactive spots differing slightly in molecular weight. This pattern was apparent in both the alpha and the beta chains. In contrast, a simpler pattern without the slight molecular weight differences was noted in HLA-DR from BM. The differences were eliminated by labeling AM and BM in the presence of tunicamycin, a specific inhibitor of protein-carbohydrate linkages of the N-glycosidic type. Thus, it appears that neutral, N-linked carbohydrate moieties account for the differences in HLA-DR molecules between AM and BM. The differential glycosylation of HLA-DR molecules in AM and BM may relate to mononuclear phagocyte development as well as antigen-presenting function.
mesh_terms: D050260:Carbohydrate Metabolism; D002241:Carbohydrates / Q000235:genetics; D004591:Electrophoresis, Polyacrylamide Gel; D006681:HLA-D Antigens / Q000235:genetics*; D006684:HLA-DR Antigens / Q000235:genetics*; D006801:Humans; D008264:Macrophages / Q000378:metabolism*; D009000:Monocytes / Q000378:metabolism*; D019158:N-Acetylneuraminic Acid; D010641:Phenotype; D011650:Pulmonary Alveoli / Q000166:cytology* / Q000378:metabolism; D012794:Sialic Acids / Q000378:metabolism
chemical_list: D002241:Carbohydrates; D006681:HLA-D Antigens; D006684:HLA-DR Antigens; D012794:Sialic Acids; D019158:N-Acetylneuraminic Acid