Techniques for Characterization of Leucocyte Antigens and Utilization of Antibodies in Therapy

Sixteen proteins were demonstrated by crossed immunoelectrophoresis (CIE) of Triton X-100 solubilized megakaryoblasts against a rabbit antiserum. One of these reacted with a recently developed monoclonal antibody (SA-1) prepared by immunization with cells from a patient with megakaryoblastic leukemia. Leukemic cells from 8/15 patients with AML stained brightly for this antigen by indirect immunofluorescence. The antiserum also stained a minor subpopulation of myelo-monocytic cells in blood and bone-marrow of healthy individuals, but not lymphoblasts from 5 patients with ALL or cells from 5 CLL patients and 4 non-Hodgkin lymphomas. The protein was shown to be amphiphilic (integral) by charge-shift CIE and hydrophobic interaction CIE with phenyl-Sepharose. It was shown not to be glycosylated by Lentil lectin affinity CIE and by Sodiumborohydride labelling. SDS-polyacrylamide gel electrophoresis of 125I (Bolton-Hunter) labelled, immunoprecipitated material demonstrated 2 bands of molecular weight 34.000 and 46.000 under reducing and non-reducing conditions.