01707nas a2200289   4500000000100000008004100001260001600042653001400058653001100072653001900083653001200102653001400114653002500128653001900153653001800172100001400190700001600204700001400220700001200234700001200246700001500258245007800273300001000351490000800361520103400369022001401403       1997                            d  c1997 Jan 1510aCytoplasm10aHumans10aInterleukin-1510aleprosy10aMonocytes10aMycobacterium leprae10aRNA, Messenger10aT-Lymphocytes1 aJullien D1 aSieling P A1 aUyemura K1 aMar N D1 aRea T H1 aModlin R L00aIL-15, an immunomodulator of T cell responses in intracellular infection.  a800-60 v1583 a<p>IL-15 is a novel cytokine with potent T cell growth factor activity. Here, we investigated the role of IL-15 in the human immune response to intracellular infection by studying patients leprosy. We found that IL-15 mRNA and protein were more strongly expressed in immunologically resistant tuberculoid patients than in with unresponsive and susceptible lepromatous patients. In vitro, Mycobacterium leprae induced IL-15 secretion from peripheral blood monocytes. Furthermore, rIL-15 by itself and in combination with rIL-2 or rIL-7 augmented PBMC proliferative responses to the pathogen. Although rIL-15 expanded the CD3-CD56+ (NK) subset, rIL-15 combined with M. leprae induced the expansion of CD3+CD56+ T cells. Immunohistologic analysis of leprosy skin lesions indicated that the frequency of CD56+ cells was greatest in the group of patients with high IL-15 expression, and that >90% of the CD56+ cells in lesions were CD3+ T cells. Therefore, IL-15 augments the local T cell response to human intracellular pathogen.</p>  a0022-1767