Human washed platelets adhere to SAA.

(A) Acid phosphatase activity as a function of cell number. Platelet suspensions containing the indicated platelet number were dispensed in triplicate wells of uncoated plates after which the acid phosphatase activity was measured as optical density (OD) increase at 405 nm. (B) Adhesion of human platelets to immobilized proteins. Platelet suspensions containing the indicated platelet number were dispensed in triplicate wells of plates coated with BSA, SAA, fibronectin (Fn), or fibrinogen (Fg) after which the adhesion assay was performed. Values are means of triplicates from one representative experiment of 3 performed. (C) Effect of Mn²⁺ and thrombin on platelet adhesion to SAA. Platelets were preincubated (15 minutes at 37°C) without (None) or with Mn²⁺ (1 mM) or thrombin (1 U/mL) and then added onto BSA- or SAA-coated wells. Values are means from 5 independent experiments (after subtracting adhesion to BSA).P < .05 when comparing adhesion with and without Mn²⁺/thrombin.