Effects of single dose compared with three days' prednisolone treatment of healthy volunteers: contrasting effects on circulating lymphocyte subsets.

AIMS To investigate the effects of longer term corticosteroid treatment on circulating lymphocyte subsets. METHODS Prednisolone (20 mg daily) was given to 12 healthy volunteers in a single morning dose for three days. Circulating lymphocyte subsets were measured by flow cytometry after whole blood lysis. RESULTS Seven hours after the first dose of prednisolone there was a significant fall in absolute numbers of lymphocytes, T cells, CD4+ and CD8+ cells, and B cells. The percentage of T cells fell significantly, due to a fall in percentage of CD4+ cells. In contrast to the seven hour findings, at 72 hours there was a significant rise in absolute numbers of lymphocytes, T cells, CD4+, CD8+, and B cells. This trend was already apparent by 24 hours. The percentage of CD4+ cells was significantly raised at 72 hours, while that of CD8+ cells had fallen significantly. The percentage of natural killer cells had fallen at 72 hours; that of B cells remained increased at 72 hours. CONCLUSIONS These findings show that corticosteroid treatment causes significant changes in lymphocyte subsets, and that such changes must be considered when designing studies of lymphocyte subsets during illness.