The antigenic structure of blood platelets. II. Histocompatibility antigens in rabbit blood platelets.

I N PREVIOUS STUDIES it was demonstrated that transplantation of skin homografts in rabbits elicited a sig ificant degree of immunity towards homologous blood platelets later infused.1’2 This demonstration that blood platelets and skin share antigens in common could not, however, lead directly to the conclusion that blood platelets contain histocompatibility antigens. It is known that transplantation immunity is a complex phenomenon during which cellular and humoral reactions are produced and that the humoral factors cannot be clearly identified with tile factor ( s) which produce accelerated rejection of a tissue subsequently transplanted.3 There is at present no method available by which transplantation immunity can be tested with certainty, other than by acceleration of homograft rejection. The question as to whether blood platelets contain histocompatibility antigens was the object of the present investigation. The results obtained indicated that the previous intradermal injection of homologous blood platelets in the rabbit could induce shortening of the rejection time of a skin homograft in a significant number of animals.