Platelet aggregation induced by antilymphocyte serum. 2. Two modes of the aggregation mechanism

The ability to inhibit the release reaction was found to correlate well with the ability to inhibit aggregation in washed human platelets exposed to antilymphocyte serum (ALS). However, the primary mechanism that contributes to ALS-induced aggregation in unwashed platelets appeared to be different from that found in washed platelets. Prostaglandin E1 and other release inhibitors were less effective in inhibiting aggregation in unwashed than in washed platelets. Salyrgan (mersalyl) in the presence of ALS or bovine fibrinogen produced an aggregation response in unwashed platelets that resembled the primary phase of aggregation. Two modes of the aggregation mechanism were evolved and are discussed.