Influence of Serum Incubation Conditions on Asolectin Thromboplastin Generation Results^{[*)] [**)]}

Summary

Thromboplastin generation in a system employing Asolectin, a soybean phosphatide, suspension as a platelet substitute is greatly influenced by the time and temperature of serum incubation.

Reproducible results and good separation of populations of normal and PTC deficient sera were obtained in the asolectin TGT system when test sera were incubated for 1 hour at 20° C prior to the thromboplastin generation test. Longer time or higher temperatures of serum incubation resulted in progressively less reliable, separation of pathologic and normal populations in asolectin TGT systems than in fresh platelet TGT systems. Cephalin suspension was shown in a smaller number of tests to behave similarly to asolectin suspension when used as a platelet substitute in TGT systems.

The 0.14 M sodium citrate eluate of citrated normal or Hemophilia B sera (incubated 1 hour at 37° C) had the ability to shorten the prolonged asolectin TGT minimal time of “over-incubated” normal sera to values obtained with the same sera in fresh platelet TGT systems. This correction, however, was probably non-specific since Hemophilia B sera results were sometimes similarly normalized. Citrated (but not oxalated) plasma incubated at 37° C for 24 hours, then recalcified to manufacture serum, and incubated an additional hour at 20° C showed no loss of the fresh 1 hour 20° C serum activity in asolectin thromboplastin generation, further suggesting that the thermolabile component of normal serum influencing asolectin TGT is a reaction product evolved during clotting.

^*) This study was supported in part by grants from the Oregon Heart Association and American Heart Association.

^**) Presented before the Western Society for Clinical Research, Carmel, California, January, 1958.

^***) (R) Registered Trade-mark.

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