A turbidimetric assay in an ELISA reader for the determination of mononuclear phagocyte procoagulant activity.

A method is described for the simultaneous determination of plasma recalcification time in 60-96 replicates. It is based on turbidimetry in a thermostatic (37 degrees C) ELISA reader photometer. Dose-response curves with thromboplastin showed a double-logarithmic correlation between recalcification time and thromboplastin concentration. Various ways of determining the coagulation time by turbidimetry were compared. Samples of mononuclear cells or monocyte-derived macrophages showed that procoagulant activity (PCA), expressed in thromboplastin units, was directly proportional to the cell number. The method may be of value for the determination of mononuclear phagocyte PCA and for the other applications of plasma recalcification time.