Adrenal Steroids and Neutrophil Mobilization

Rats were challenged to mobilize neutrophils by intraperitoneal injection of a bacterial extract. Adrenalectomized rats were able to accomplish this as well as their sham-operated controls. Furthermore, pretreatment of intact animals with moderate doses of cortisol injected subcutaneously did not produce a detectable effect upon neutrophil mobilization. On the other hand, when massive, pharmacologic doses were injected subcutaneously, significantly fewer neutrophils appeared in the peritoneal fluid. Inhibition of neutrophil accumulation was noted when the steroid was injected locally; this was accomplished with relatively small doses when calculated in terms of body weight. The relative ineffectiveness of subcutaneous injection compared with topical administration suggests a direct effect of the hormone, probably upon small blood vessels.