THE QUANTIFICATION OF ERYTHROCYTE ANTIGEN SITES WITH MONOCLONAL-ANTIBODIES

Abstract

The application of monoclonal antibodies to the quantification of blood group antigen sites on [human] erythrocytes was examined. A 2nd antibody technique useful labeled anti-mouse IgG could not be used as it was not possible to predict the binding ratio between this and the monoclonal antibody. A seies of monoclonal antibodies (R10, R18, BRIC 13, BRIC 14) to the erythrocyte sialoglycoprotein .alpha. (syn: glycophorin A) showed the number of antigen sites to be from 0.3 .times. 106-1.2 .times. 106/erythrocyte and supported the conclusion that the Wrb antigen is located on this protein. An antibody with a specificity related to the Rh blood group system (R6A) showed 4.6-10.4 .times. 104 binding sites to be present on cells of phenotype cCDEe. On cells of phenotype -D-1.24 .times. 104 binding sites were present but protease treatment increased the number of available sites to 1.3 .times. 105. An antibody to a Kell-related antigen (BRIC 18) recognized 2.5-5.9 .times. 103 sites per erythrocyte on cells of phenotype Kk. A similar number also appeared to be present on cells of the McLeod and Ko phenotypes although the affinity for the antigen on these cells was very much reduced. The potential of using monoclonal antibodies for this purpose and the value of this in the study of blood group systems has been demonstrated.