Measuring platelet and leucocyte aggregation/adhesion responses in very small volumes of whole blood.

A technique is described by which leucocyte and platelet aggregation may be measured in 100 microliter (or less) of citrated whole blood. The blood is first diluted in a balanced salt solution and aggregation responses measured with an electronic aggregometer. Leucocytes may be aggregated with substances such as the chemotactic peptide f-met-leu-phe, and platelets with the conventional agents such as ADP or collagen. The response of the leucocytes to f-met-leu-phe is very sensitive to the inhibitory activity of mepacrine. The aggregation of platelets, but not leucocytes, is blocked by low concentrations of indomethacin. The technique is useful for drug screening, diagnostic purposes, ad investigating platelet and leucocyte pharmacology and physiology.