Cell-cell interaction in human granulopoiesis: role of T lymphocytes

Abstract

T lymphocytes have been implicated in the pathogenesis of granulocytopenias. We studied the effects of unstimulated and pokeweed mitogen (PWM) activated intact (Ti) and partially purified T cell subpopulations (T gamma and Tnon gamma, i.e., T mu plus T0) on in vitro granulocyte-macrophage colony formation (CFUGM) by autologous normal human bone marrow (BM). Coculture of BM and Ti, T gamma, or Tnon gamma caused only a slight decrease in the numbers of colonies and clusters; however, when cultured with a mixture of T gamma and Tnon gamma, the inhibition was significant. In contrast, activation of T cells or T cell subsets with PWM resulted in a marked decrease in colony formation. These results demonstrate that: 1) PWM-activated T cells or its subpopulations will inhibit autologous BM colony formation in vitro. The suppression seen with admixes of unstimulated T gamma and Tnon gamma is presumptive evidence that prior cell-cell interaction(s) may be required for the generation of inhibitory cells in this system; and 2) this model may represent an in vitro counterpart of immune-mediated cytopenias in man.