Biochemical characterisation studies on a leukocyte alloantigen expressed with high frequency in leukaemia patients.

In this report we describe, using a previously characterised monoclonal antibody (NC-2), the biochemical characteristics of a human leukaemia-associated alloantigen. Two proteins with molecular weights of 50 kDa and 15 kDa were immunoprecipitated from 125I surface labelled HL-60 cells. Both proteins appeared to be sensitive to digestion with trypsin, the 50 kDa protein in particular. Treatment with glycopeptidase F indicated the presence of N-linked oligosaccharides, whereas treatment with neuraminidase had no effect on the mobility of the antigens in SDS-PAGE indicating the absence of detectable sialic acid residues. Sensitivity to glycopeptidase F indicates that the reacting antigens are glycoproteins in nature. The antibody reacts with a range of normal tissues and appears to be associated with cytoplasmic granules in HL-60 cells.