Myeloid-associated antigen 3-alpha-fucosyl-N-acetyllactosamine (FAL): location on various granulocyte membrane glycoproteins and masking upon monocytic differentiation.
Seven different granulocyte-reactive murine monoclonal antibodies (mAb) were studied. The antigens recognized by these mAb were immunoprecipitated from lysates of 125I-labeled granulocytes of healthy donors. The isolated antigens were analyzed by electrophoresis on sodium dodecyl sulfate-polyacrylamide gel and autoradiography. All 7 antibodies precipitated the same 6 membrane polypeptides from membrane-iodinated granulocyte lysates: 105 and 150-kDa as most pronounced, together with 260-, 230-, 67- and 52-kDa polypeptides. One of the antibodies studied, B4.3, is directed against 3-alpha-fucosyl-N-acetyllactosamine as shown by absorption with the synthesized carbohydrate molecule. Competition experiments with 125I-labeled B4.3 demonstrated complete inhibition of binding by B4.3 and 3 of the other antibodies (VM D5, UJ308, MI/N1) and partial inhibition by the 3 other antibodies (FMC 10, FMC 12, FMC 13), indicating binding to the same antigenic structure. None of the 7 mAb reacted with monocytes in the immunofluorescence technique, but after neuraminidase treatment of these cells, positive reactions were obtained with all mAb. Immunoprecipitation with lysates of both native and neuraminidase-treated monocytes showed no polypeptide bands. Monocytic differentiation of the cell line HL60 by 12-O-tetradecanoylphorbol-13-acetate (TPA) and of cell line U 937 by dimethylsulfoxide and TPA was accompanied by a decrease in reactivity with these antibodies, which could be recovered by neuraminidase treatment. This indicates that 3-alpha-fucosyl-N-acetyllactosamine is masked for the detection of the antibody upon monocytic differentiation by sialylation.
D000911:Antibodies, Monoclonal; D000954:Antigens, Surface / Q000276:immunology*; D002454:Cell Differentiation; D000939:Epitopes; D006023:Glycoproteins / Q000276:immunology*; D006098:Granulocytes / Q000166:cytology / Q000276:immunology*; D006801:Humans; D016256:Lewis X Antigen / Q000276:immunology*; D008565:Membrane Proteins / Q000276:immunology; D008970:Molecular Weight; D009000:Monocytes / Q000166:cytology / Q000276:immunology*; D009844:Oligosaccharides / Q000276:immunology*
D000911:Antibodies, Monoclonal; D000954:Antigens, Surface; D000939:Epitopes; D006023:Glycoproteins; D016256:Lewis X Antigen; D008565:Membrane Proteins; D009844:Oligosaccharides