Il15+Il15r complex is a a pleiotropic cytokine of the interleukin family of proteins that plays important roles in the innate and adaptive cell homeostasis, as well as peripheral immune function. The encoded protein undergoes proteolytic processing to generate a mature cytokine that stimulates the proliferation of natural killer cells. The transgenic mice overexpressing the encoded protein exhibit an increase in the number of memory CD8+ T cells in a naive state and enhanced protection against bacterial infections. Mice lacking the encoded protein exhibit impaired protection against a strain of attenuated Mycobacterium.