Recombinant IL7 is a bioactive protein intended for use in cell culture applications. IL7 stimulates the proliferation of pre-B and pro-B cells. IL7 also supports the maturation of megakaryocytes. ED50 range = 0.2 to 1 ng⁄mL (Specific Activity: 5.0 x 10^6 to 1.0 x 10^6 units⁄mg), determined by the dose dependent proliferation of human PBMCs. Optimal concentration for individual application should be determined by a dose response assay.