Identification of the Yukb allo-antigen on platelet glycoprotein IIIa.

The glycoprotein (GP) localization of a new platelet-specific allo-antigen Yukb is described. The antibody was isolated from serum of a patient with neonatal allo-immune thrombocytopenia. In immunoblot procedure, it bound exclusively to platelet GP IIIa, like anti-PlA1, while the known anti-Baka and anti-Leka reacted with GP IIb. Analysis of GP from chymotrypsin-treated platelets with anti-Yukb revealed no binding in the 68-kilodalton position while anti-PlA1 did. Thus, unlike the PlA1 antigen, the Yukb determinant either resides on the 30-kilodalton fragment of GP IIIa or it is destroyed by chymotrypsin treatment.