Effect of corticosteroid treatment on hemopoiesis in vivo and in vitro in a patient with Felty's syndrome.

We have studied the CFU-GM and BFU-E in vitro growth in a neutropenic and anemic patient with Felty's syndrome, either before or one and three months after steroid therapy when neutrophils and erythrocytes returned to normal. Both CFU-GM growth and CSA production were found to be low before therapy, and prednisone was shown to raise them to normal levels. The in vitro growth of BFU-E and the production of BPA by T lymphocytes of the patient were significantly lower than normal when studied before therapy. However, the T lymphocytes incubated in vitro with hydrocortisone regained their ability to stimulate the BFU-E growth. After prednisone therapy both BFU-E growth and BPA production by T lymphocytes returned to normal. Possible pathogenetic mechanisms of impaired granulo- and erythropoiesis in Felty's syndrome are discussed. The in vitro study with hydrocortisone can help to identify steroid-sensitive patients.