IL7 is a hematopoietic growth factor constitutively produced by stromal cells from the bone marrow and thymus. It is critical for B and T cell development and survival. IL7 promotes the differentiation of hematopoietic stem cells to lymphoid precursor cells by binding to a receptor composed of common gamma chain and IL-7Ra (CD127). Lymphoid precursor cells give rise to T cells, B cells, and natural killer cells. Furthermore, IL7 provides signals to regulate the survival of naive and memory CD4+ and CD8+ T cells NK T cells, innate lymphoid cells, and T regulatory cells. During B-cell development, IL7 also provides signals to promote survival, proliferation and differentiation. Recombinant mouse IL7 is a non-glycosylated protein with a molecular mass of 15.2 kDa.