Hydrocortisone both decreases the up-regulation of complement receptors CR1 and CR3 and the ingestion process of human granulocytes.

We have studied the effect of hydrocortisone on the complement receptor expression (CR1 and CR3) of human granulocytes during the up-regulation phase and the following stable period when exposed to N-formyl-methionyl-leucyl-phenylalanine (fMLP) or the medium alone at 37 degrees C. The receptor expression was also correlated to the C3bi-mediated phagocytosis with special reference to attachment and ingestion. The results showed that after incubation with fMLP the increased expression of CR1 and CR3 is accompanied by an increased ingestion, but not attachment, of complement-opsonized yeast particles. This increase was significantly lower with regard both to attachment and ingestion, as well as receptor expression if hydrocortisone was present during the up-regulation phase. However, the addition of hydrocortisone after the up-regulation of fMLP-treated granulocytes decreased the ingestion of particles but not the CR1 and CR3 expression. The results indicate a membrane effect of hydrocortisone that affects both the receptor mobilization and ingestion mechanism of the phagocytes.