Date of Award

Spring 1998

Degree Type

Thesis - Restricted

Degree Name

Master of Science (MS)

Department

Biology

Abstract

Among Japanese, about 6% of normal group A1 and B individuals express high levels of the corresponding antigens on their platelets; thus transfusion of group B "high expresser" platelets into a group 0 recipient resulted in a poor therapeutic response. In the present report, A1, B, and H antigen levels were measured on platelets from Caucasian Americans using specific monoclonal and polyclonal antibodies and flow cytometry. Seven percent (7 of 100) of group A1 and 4% (4 of 100) of group B donors were found to express high levels of the corresponding antigens on their platelets. Two forms of the i high expression platelet phenotype were observed for group A1 individuals, "Type f' and "Type IT." Type I individuals had high levels of A1 antigens on their platelets, but showed a heterogenous distribution of these antigens as seen with normal expression platelets. Type IT individuals showed very high levels of A1 antigens on their platelets, but with a homogenous distribution. Serum A1- and B-glycosyltransferase activity was significantly higher for Type IT subjects compared to Type I (p = 0.02) or normal expressers (p = 0.03). ELISA and Western blot analysis of Type IT high expression platelets showed that the majority of the A1 antigens are carried on GPllb and PECAM (CD31 ). In addition, two fathers in suspected cases of neonatal alloimmune thrombocytopenic purpura (NATP) were found to have the Type IT high expression platelet phenotype, and no plateletreactive antibodies other than anti-A,B could be detected in the maternal sera suggesting that the high expression platelet phenotype could be a contributing factor in some cases of unexplained NATP. Family studies demonstrated dominant inheritance of the Type IT high expression phenotype. The implications of these findings in platelet transfusion and other immune platelet disorders deserves further study.

Share

COinS