Species differences in platelet agglutination in man and in the dog, swine and rabbit

Abstract

The in vitro agglutination of platelets by incubated plasma-cation mixtures was studied in man and in the dog, swine and rabbit. A macroscopic agglutination test previously described was used. In homologous tests TAg activity was demonstrated in swine and in the dog. TAg is a thrombocyte agglutinating factor not adsorbed by BaSO₄ and active with Mg⁺⁺ and Mn⁺⁺. In all species agglutination also occurred with Ca⁺⁺ and whole plasma; in the dog and in man this activity was removed from plasma by BaSO₄ adsorption, and in the dog was recovered in the eluate. This agglutinating factor is tentatively designated TAg'. In the rabbit and in swine, platelets were agglutinated with adsorbed plasma and Ca⁺⁺ From studies with heterologous mixtures of plasma and platelets, it was concluded that the platelet rather than the plasma determines species differences in cation requirements and agglutinability. All plasmas studied cause platelet agglutination characteristic of the platelet species if appropriate cations are present. Porcine plasma appears to contain a heterophil antibody for human platelets.