Summary
Through an investigation of the influence of platelet activity on the initiation of clotting by glass contact the following results were obtained:
1. There was no correlation between platelet count and platelet activity in centrifuged plasma.
2. When platelet-rich plasma was treated by excess of powdered glass the activated “foreign surface factor“ (FSF) in plasma was removed by the glass powder.
3. When glass treated high-spun plasma was stored for 24 hours in siliconized tubes all the activity was lost, whereas in samples of glass treated platelet-rich plasma most of the activity remained.
4. It was possible to produce higher FSF activity when the platelet-poor plasma prior to treatment by glass was either adsorbed by BaSO4 or diluted 1: 10.
5. FSF activity was removed when activated plasma was treated with BaSO4. All the results, as well as many contradictory results obtained by other investigators, can be explained by suggesting the presence of an inhibitor in plasma, which reacts against activation of the precursor of the “foreign surface factor“ (pro-FSF). This inhibitor is neutralized by a platelet factor. The active FSF might be identical with activated PTA.
