Mouse monoclonal IgM antibody against human lung cancer line SK-LC-3 with specificity for H(O) blood group antigen.

Spleen cells from mice immunized with the human lung cancer line SK-LC-3 were fused with mouse NS-1 myeloma cells. One of the hybrid clones produced a monoclonal IgM antibody (designated F-3), detected with antimouse Ig-MHA and hemagglutination assays. This antibody was completely absorbed by O red cells and completely inhibited by low concentrations of H(O) glycoproteins and hog mucin (A + H). Bombay (Oh) red cells completely failed to absorb F-3 activity even after treatment with neuraminidase. A1, A2, A1B, A2B, and B red cells and A- and B-glycoproteins were less effective in absorbing or inhibiting F-3 activity. Other glycoproteins (including those having Lea or blood group precursor structures) showed little or no inhibitory activity. Serum from nude mice carrying F-3 hybridoma agglutinated O and A2 red cells at a titer of 1:40,000 and 1:640, respectively. A1, A1B, A2B, and B red cells were agglutinated with titers of 1:80 or less. Monoclonal antibody F-3 is, therefore, highly specific for H(O) blood group determinants.