T-lymphocyte--mediated granulopoietic failure. In vitro identification of prednisone-responsive patients.

To identify patients with T-lymphocyte--mediated granulopoietic failure, we compared clonal growth of unfractionated bone-marrow cells with that of autologous marrow cells from which T lymphocytes had been removed, in a group of 234 patients. We also attempted to identify prednisone-responsive patients by culturing both unfractionated and T-depleted cells with and without glucocorticoids in vitro. Ninety-three patients were treated with prednisone for two to four weeks. Neutropenia resolved in 24 of 25 patients whose colony growth was enhanced by glucocorticoids in vitro, but in none of 68 whose cultures showed no response (P = 10(-10). Hemopoietic inhibitory T cells were found in 21 of the 24 prednisone-responsive patients. When these 21 patients were restudied during steroid treatment, the hemopoietic inhibitory cells were undetectable in steroid-responsive patients but were present in steroid-resistant patients. T lymphocytes can mediate granulopoietic failure in a variety of conditions, and in vitro studies identify most of the patients with these conditions. Hemopoietic inhibitory T cells are often steroid-sensitive, and in vitro study accurately predicts responses to steroid therapy.