Increased platelet aggregation due to plasma-aggregating activity. Identification of the responsible factors.
Platelet-poor plasmas (PPPs) from 52 out of 71 patients affected by different diseases and selected for increased amounts of circulating platelet aggregates, incubated at 37 degrees C for 30 min with control platelet-rich plasma (PRP; cross-matching test) induced the formation of platelet aggregates, stimulated the production of malondialdehyde and enhanced ADP-induced aggregation. 31 control PPPs were consistently negative at cross-matching test. Gel chromatography of plasmas on agarose 4% allowed the identification of four different fractions (A, B, C, D) provided with aggregating activity. Fraction A eluted at the void volume was to be identified with the von Willebrand factor, whereas B, C and D fractions, eluted at the same elution volumes as activated factor X were mainly composed of factor X (fraction B) and activated factor X (fractions C and D). Thrombin activity was absent in all the fractions provided with aggregating activity. Also, from control PPPs negative at cross-matching tests, the same fractions could be obtained, although of 5--10 times lower aggregating potency, thus explaining the negative cross-matching tests. These findings stress the role of some extraplatelet factors related to hypercoagulability in platelet hyperaggregability.
D000244:Adenosine Diphosphate / Q000494:pharmacology; D000293:Adolescent; D000328:Adult; D000536:Aluminum Hydroxide / Q000494:pharmacology; D001779:Blood Coagulation Factors / Q000302:isolation & purification / Q000494:pharmacology*; D001793:Blood Preservation; D002850:Chromatography, Gel; D005169:Factor VIII / Q000032:analysis; D006801:Humans; D010974:Platelet Aggregation / Q000187:drug effects*
D001779:Blood Coagulation Factors; D000536:Aluminum Hydroxide; D000244:Adenosine Diphosphate; D005169:Factor VIII