A diffusible stimulator of eosinophilopoiesis produced by lymphoid cells as demonstrated with diffusion chambers

Previous experiments have indicated that eosinophilopoiesis is stimulated in lymphoid cell-dependent eosinophil responses to certain antigens. In order to study if the potential for this stimulation of eosinophilopoiesis is a function of lymphoid cells and can be expressed on challenge with the eosinophilia-inducing antigen, the diffusion chamber technique for the culture in vivo of murine hemopoietic cells has been modified. A quadrachamber diffusion assembly allows for the simultaneous maintenance in the same host of four cell populations, pairs of which are separated by a cell-impermeable Millipore diffusion membrane of defined porosity. Spleen cells for chambers were from normal mice and mice primed with tetanus toxoid; secondary challenge induces eosinophilia. These spleen cells were placed transfilter from isogeneic bone marrow cells and cultured in vivo for 6 days in normal mice that received tetanus toxoidintraperitoneally following chamber- assembly implant. The marrow cell transfilter from spleen cells of primed-donor origin exhibited significantly greater eosinophilopoiesis than contiguous-chamber marrow transfilter from normal spleen cells. Such stimulated eosinophilopoiesis was independent of total chamber marrow cellularity. The data indicated that antigen-stimulated lymphoid cells may be the source of an eosinophilopoietic factor.