Human Interleukin-3-Like Activity, Basophil and Eosinophil Growth Promoting Activities and Colony Stimulating Factor Derived from Several Cell Lines

Human IL-3-like activity, colony stimulating factor (CSF) and basophil/eosinophil growth promoting activity (Ba/Eo GPA) in serum-free conditioned media (CM) derived from various cell lines of human origin were examined. Squamous cell carcinoma (Colo-16), osteogenic sarcoma (R97KL4) and human placental (HP) cells produced 10-20% IL-3 activity present in supernatants from a mouse myelomonocytic cell line (WEHI-3BCM) when assayed using a murine IL-3 dependent cell line (32Dcl/H4). The human T-cell leukemic cell line (Mo) and several neuroblastoma cell lines did not produce IL-3-like activity, nor did purified human erythroid potentiating activity (EPA) from Mo contain IL-3. CSF and Ba/Eo GPA were detected in CMs from Mo, HP, Colo-16 but not from R97KL4. No IL-2 activity was detected in any of these CMs. These observations point to the existence of diverse sources of human IL-3-like activity and to the probable distinctiveness of human IL-3, basophil or eosinophil GPA, and EPA. Analogies drawn between human and murine hemopoietic activities need to be made with caution.