Nobuyuki Tanigaki

IgM and IgG anti-hapten antibody: hemolytic, hemagglutinating and precipitating activity.

Summary Hemolytic and hemagglutinating activities of IgM and IgG antibody against the p-azobenzenearsonate (Rp) group were compared using purified antibody preparations. IgM antibody showed a considerably higher activity in both hemolytic and hemagglutinating systems. The hemolytic and hem-agglutinating activities of IgM antibody were both 180 to 60 times higher on a molar basis than those of IgG antibody when measured with erythrocytes to which Rp-groups were attached. The reduced-alkylated product of IgM antibody showed little activity in both hemolytic and hemagglutinating systems, although the reduced-alkylated product had been shown previously to retain hapten-binding activity. IgM antibody also lost precipitating activity with a polyvalent hapten-protein conjugate upon reduction and alkylation. Loss of hemagglutinating and precipitating activities is probably due to univalency of 6S subunits produced by reduction.

The Basic Structure and the Antigenic Characteristics of HL‐A Antigens

In this report, we are giving results that we have obtained in our laboratory conceming the nature of the HL-A antigen molecule. HL-A antigen molecules were isolated from human lymphocytes grown in continuous culture. The cell membrane components were obtained from cells dismpted mechanically by shaking and were then digested with papain to give soluble HL-A antigen molecules of essentially 48,000 daltons for any of the several HL-A specificities studied. It was possible, moreover, to separate some of the HL-A molecules on the basis of electrophoretic mobility in column electrophoresis experiments. It was found that all the HL-A molecules could be dissociated in two fragments on exposure to acid or various dissociating agents. One fragment was 33,000 daltons and the other 11,000 daltons. The 33,000 dalton fragment appears to be the part of the original 48,000 dalton HL-A molecule which is responsible for the HL-A specificity. However, it appears that the HL-A specificity is due to the protein component of the 33,000 dalton fragment and that during the isolation of the fragment there is a change in conformation which decreases the HL-A activity. The 11,000 dalton fragment seems to be a fragment common to all the HL-A molecules and has been identified as the same as the /?2-microglobulin molecule originally isolated from urine by BerggSrd & Beam (1968). The

Human Transplantation Antigens: Isolation and Radioimmunoassay

Summary Human transplanation antigens, HL-A1 and HL-A2, have been obtained from cells of a single hematopoietic line which has both antigens. HL-A1 has been obtained essentially free of HL-A2. Both have a molecular weight of about 48,000. They appear to be of protein nature and can be labeled with radioiodine. The radioactive antigens permit the use of sensitive radioimmunoassay methods for identifying and quantitating HL-A antigens.