Isolation and serological characterization of a monoclonal antibody recognizing the N blood group antigen

A mouse hybridoma has been isolated which secretes a hemagglutinating monoclonal antibody (MoAb) recognizing the N and ‘N’ blood group antigens. This conclusion is based upon the following observations. First, all red cells expressing either N or one of the alleles of Ss (ie, ‘N’ were strongly agglutinated by the MoAb diluted fourfold. The only cells not reactive were of the M+N‐S‐s‐(U‐) and M+N‐S‐s‐(U+) phenotype and cells (J.R. and A.G.) expressing Lepore‐type hybrids of the MN and Ss sialoglycoproteins, which do not express N or ‘N’. Secondly, red cells of the N+S‐s‐(U‐) phenotype were rendered unreactive to MoAb following treatment of the cells with trypsin, which is known to destroy N antigen activity. Conversely, cells expressing S and/or s maintained their reactivity with MoAb following trypsin treatment, which does not cleave ‘N’ from the Ss sialoglycoprotein. When spent culture medium containing MoAb was diluted and tested against a panel of red cells, the antibody titer fell into two distinct categories depending upon the MNSs phenotype of the target. Red cells expressing either homozygous or heterozygous N‐sialoglycoprotein (N‐ SGP) were agglutinated by 128‐fold diluted MoAb. In contrast, a 16‐fold dilution of MoAb was the endpoint for agglutination of cells lacking N‐ SGP, but expressing S and/or s. 1984 AABB