Mouse interleukin-7(IL-7) is the member of hemopoietin family which is important to the differentiation, proliferation, and survival of lymphocyte. Mouse IL-7 shares approximately 88% aa sequence identity with rat IL-7 and 58-60% with human, equine, bovine, ovine, porcine, feline and canine IL-7. It is widely expressed in primary and secondary lymphoid tissues cell and stromal epithelial cells of the thymus, bone marrow, and intestines. IL-7 activation of IL-7 R alpha is critical for both T cell and B cell lineage development. It is important for proliferation during certain stages of B-cell maturation. IL-7 contributes to the maintenance of all native and memory T cells, mainly by promoting expression of the anti-apoptotic protein Bcl-2. It is required for optimal T cell-dendritic cell interaction.