CD43 monoclonal antibodies recognize the large sialoglycoprotein of human leukocytes.

In this study data are presented indicating that the molecule identified by the recently described CD43 cluster of monoclonal antibodies (mAb; Oxford, 1986) is the human analogue to the one originally described in rat as leukocyte sialoglycoprotein (LSGP). This conclusion is based on several criteria. Both molecular mass (105 kDa) and cellular distribution are similar to the antigens previously described in the rat with the mAb W3/13 and subsequently in humans with L10 mAb. Sialidase treatment of the molecule immunoprecipitated by 84-3C1 mAb (CD43) resulted in a decreased electrophoretic mobility on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. L10 mAb inhibited the binding of 84-3C1 mAb to the cell membrane suggesting that both mAb recognized the same molecule. Moreover, the presence in the CD3-4-8- thymic populations of the sialidase-sensitive epitope recognized by mAb 84-3C1 suggests that there is no simple correlation between the thymic maturation and the degree of sialylation.