Background: The extent of expression of the blood group A on platelets is controversial. Further, the relation between platelets' blood group A expression and the titers of isoagglutinins has not been thoroughly investigated, so far.
Methods: We evaluated the relation between the genotype with platelets' blood group A and H expression estimated by flow cytometry and the titers of isoagglutinins.
Results: The A expression varied between genotypes and within genotypes. However, the expression in A1 was stronger than in all other genotypes (p < 0.0001). An overlap of expression levels was apparent between homozygous A1A1 and heterozygous A1 individuals. Still, The A1A1 genotype is associated with a particularly high antigen expression (p = 0.009). Platelets' A expression in A2 versus blood group O donors was also significant (p = 0.007), but there was again an overlap of expression. The secretor status had only little influence on the expression (p = 0.18). Also, isoagglutinin titers were not associated with genotypes.
Conclusion: To distinguish between A1 and A2 donors may reduce incompatible platelet transfusions and therefore be favorable on platelet transfusion increment. Clinical data are needed to support this notion.
Keywords: Blood group A; Flow cytometry; Genotype; Isoagglutinins; Platelets.