METHODS

Material. Whole blood donations were obtained from volunteer medical staff and patients. In many instances in sitro studies were done using blood obtained from therapeutic phlebotomies. Preparation of platelet suspension. The following technique was derived from past experience in the preparation of platelet suspensions using plastic bag equipment. Five hundred ml. of whole blood is collectedby gravity into polyvinyl chloride plastic bags (Fenwal Laboratories) containing 50 ml. of 1.5 per cent disodium ethylene-diaminetetracetic dihydrate (NaEDTA) in saline. As noted previously (16) Arquad04-coated 15 gauge male-hub needles are used. The plastic tubing leading from the needle to the plastic bag has a" Y" type division that allows 10 ml. of blood to be withdrawn to exclude tissue juice contamination and to evaluate venous blood flow. The whole blood is centrifuged at 2 C. for 15 minutes at 1,300 rpm.(325 G) in an International Centrifuge, Model PR-2. After centrifugation, the platelet-rich plasma is transferred to another plastic bag containing 15 ml. of2 per cent Triton® 5 in saline using a piercing

'Arquad® is a trade-mark of Armour Chemical Division, Armour and Co., Chicago, for Tris (2-hydroxy-ethyl) dodecylamine and N, N'(2, 3-dihydroxypropyl)-N-alkyl-trimethylenediamine (A-15). 5Triton® is a trade-mark of Rohm & Haas Co., Phila-delphia, for oxyethylated tertiary octyl phenol formalde-1257