Title: Interleukin-4 (B Cell Growth Factor-II/Eosinophil Differentiation Factor) is a Mitogen and Differentiation Factor for Preactivated Murine B Lymphocytes
Abstract: Type II B cell growth factor (BCGF II) was originally detected by its capacity to induce proliferation of the murine B cell lymphoma BCL. in vitro (Swain & Dutton, 1982: Swain et al, 1983). Its effects on normal B cells have not been well defined, since it has proved difficult to separate BCGF II from other potentially relevant factors. We have recently described a novel source of BCGF II which is free of any other lymphokine believed to act on B cells. This activity is produced by a murine T cell hybrid NIMP-TH1, which was selected for its capacity to secrete the eosinophil differentiation factor (EDF) (Warren & Sanderson, 1985: Sanderson et al, 1986). The BCGF II and EDF co-purify in every fractionation procedure employed (Fig. 1): both activities migrate with an approximate Mr of 44,000 (Fig. 2) and a pi of approximately 5.0 (unpublished data). These findings, together with earlier evidence that BCGF II and EDF are co-ordinately produced by a large panel of T cell clones (Sanderson et al, 1985) strongly suggested that the two activities are due to the same molecule, which has therefore been named interleukin 4 (IL-4) (Sanderson et al, 1986). We have examined the effects of this factor on normal murine B cells.