Changes in the concentration of leucocytes and platelets in the peripheral blood during sterile inflammation in rabbits.

Glycogen in isotonic saline was infused into the peritoneal cavities of rabbits to produce sterile inflammation. This caused a small increase in the haematocrit value and larger decreases in the concentrations of circulation leucocytes and platelets. Circulating granulocytes decreased by about 40% in 2 h and increased in the next 2 h to about 4 times their initial concentration. Acetyl salicyclic acid (ASA) (10 mg/kg) infused with the glycogen did not affect the decrease significantly but accelerated the subsequent increase. Circulating mononuclear leucocytes, mostly lymphocytes, decreased progressively by about 75% after 4-5 h. This decrease was not affected by ASA. Circulating platelets decreased by about 30% in the first hour; this decrease was accelerated and augmented by ASA. Subsequently the platelet concentrations remained constant for at least 4-5 h. Glycogen so infused is known to activate complement, and ASA to inhibit prostaglandin synthetase. Therefore the results suggest that (i) the initial decrease in circulating granulocytes is mediated by activated complement; (ii) the emigration of granulocytes from blood into the inflammatory exudate is increased by prostaglandins; (iii) the initial decrease in circulating platelets is mediated by activated complement and antagonized by prostaglandins; and (iv) the decrease in circulating lymphocytes is mediated by activated complement and uninfluenced by prostaglandins.