On the Effects of a Hemostasis Activating Factor (HaF) from Subcutaneous Tissue on Platelet Retention

Extracts of human subcutaneous tissue with a very low thromboplastic activity strongly stimulate platelets (sphering and pseudopode formation) within seconds if added to blood directly at blood sampling (30 μ/ml citrate blood). To study the effect of this hemostasis activating factor (HaF) on platelet retention a special glass bead column with basically low retention (0-15 % in healthy individuals) was prepared. If HaF 50μl/ml) was added to freshly drawn citrate blood retention was increased from a mean of 12 % to a mean of 57 %. Even higher retention rates were obtained by adding a cryoprecipitate from normal PPP (50μl/ml) together with HaF. 100μl/ml of cryoprecipitate markedly enhanced platelet retention. Feiba_R (Immuno) alone did not increase platelet retention. Together with HaF Feiba_R (50μl/ml citrate blood) induced a 85% retention. The enhancing effect of HaF on platelet retention is probably caused by rapid platelet stimulation and may be an essential trigger mechanism for primary hemostasis.