Interleukin 2 stimulates the T‐cells from patients with eosinophilia to produce CFU‐Eo growth stimulating factor

To explore the mechanism of eosinophilopoiesis in patients with reactive eosinophilia, we studied the effect of interleukin 2 (IL-2) on the production of CSFs, especially CFU-eosinophil growth stimulating factor (CFU-Eo GSF) from T-lymphocytes in patients with reactive eosinophilia. Conditioned media (CM) prepared from patients' E rosette forming cells (ERFC) with or without IL-2 was assayed for CFU-Eo, CFU-monocyte, macrophage (CFU-M) and CFU-neutrophil (CFU-N) GSF. The addition of IL-2 to the ERFC significantly stimulated the production of CFU-Eo and CFU-M GSF while only CFU-M GSF increased in normals. Serial testing of the CFU-Eo GSF in ERFC-CM demonstrated that the ability of ERFC to produce CFU-Eo GSF with IL-2 stimulation was retained even when the eosinophilia had disappeared. These results suggest that CFU-Eo GSF is produced from T-cells with IL-2 stimulation and that the T-cells from patients produce IL-2 stimulation and that the T-cells from patients produce CFU-Eo GSF with IL-2 stimulation after the disappearance of eosinophilia.