Analysis of the effect of an anti-inflammatory steroid, dexamethasone, on neutrophil chemotaxis in the Boyden chamber with a modified 51Cr-labeling method.

For the determination of leukocyte chemotaxis in the Boyden chamber toward zymosan-activated serum, a modification of the 51Cr-labeling method originally introduced by Gallin et al. was made using a polycarbonate filter at the top of a double filter system. By application of this method, it was demonstrated that an anti-inflammatory steroid, dexamethasone at relatively low doses, directly inhibited chemotactic movement of leukocytes after the pretreatment of the cells with dexamethasone for several hours. This inhibitory effect was proved to be a common property of glucocorticoids. The leukocyte-inhibitory effect manifested within the cell body and the release of any extracellular factors mediating the inhibitory effect of the corticoid into the medium was not demonstrated. The present data suggests that the inhibitory effect of dexamethasone on leukocyte infiltration observed in vivo is attributed to the direct inhibitory effect of dexamethasone on the motility of leukocytes.