A Monoclonal Antibody Against a Burkitt Lymphoma Associated Antigen Has an Anti-Pk Red Blood Cell Specificity

The blood group specificity of a rat IgM monoclonal antibody (38-13) directed against most EBV-positive or -negative Burkitt's lymphoma was investigated. The target antigen was previously identified as the neutral glycolipid ceramide trihexoside (CTH), a substance which accumulates in red cells from very rare individuals of the Pk phenotype and which appears as a normal intermediate in the biosynthetic pathway of the P blood group antigen (globoside). The 38-13 antibody agglutinated Pk1 and Pk2 red cells at 4 degrees C with a very high titre but was inactive against native P1, P2 and p erythrocytes, although a very weak activity was noticed towards papain-treated P1 and P2 erythrocytes. These results were confirmed by an indirect radio-binding assay which also demonstrated that the 38-13 antibody reacted with lymphocytes, fibroblasts and EBV-positive lymphoblastoid cell lines derived from Pk1 and Pk2 individuals but not from other donors. These findings demonstrate that the 38-13 monoclonal antibody previously considered as specific of Burkitt cells could be routinely used as an anti-Pk blood group typing reagent. The mechanism of CTH accumulation in Burkitt cells and Pk red cells is probably different and might be associated respectively with the activation of an alpha-4-galactosyltransferase or the genetic blockage of a beta-3-N-acetylgalactosaminyltransferase.