Analysis of Cell Surface Molecules on Human Platelets with Monoclonal Antibodies

Abstract
The effects of 18 monoclonal antibodies (α-GPIb, α-GPIIb-IIIa, α-gp78, and α-p151) on platelet function were examined. Four anti-GPIIb-IIIa antibodies and twelve anti-GPIb antibodies were classified into two groups depending on their binding specificities in assays of antibody binding blocking. Of the four anti-GPIIb-IIIa antibodies, three completely inhibited platelet aggregation induced with ADP or collagen, while the other caused only partial inhibition. The first three antibodies showed identical specificity in antibody binding blocking assays. Of the twelve anti-GPIb antibodies, 4 completely inhibited platelet aggregation induced with ristocetin, 2 inhibited it partially, and the other 6 antibodies did not inhibit it at all. No direct correlation was observed between the ability of the antibodies to inhibit platelet aggregation and their binding specificities. The monoclonal antibodies anti-gp78 and anti-pl51 did not affect any of the platelet functions examined.