IL-15-mediated induction of LFA-1 is a late step required for cytotoxic differentiation of human NK cells from CD34+Lin- bone marrow cells.
Optimal differentiation of cytotoxic NK cells is important to provide protective innate immunity to patients after bone marrow transplantation. In vitro differentiation of CD56(+)CD3(-) NK cells takes weeks and is supported by several cytokines, including IL-2, IL-7, and IL-15, and thus can be useful for immunotherapy. However, IL-2 therapy is problematic in vivo, and NK cells differentiated in vitro with only IL-7 lack cytotoxicity. We assessed whether human NK cells initially differentiated in vitro from CD34(+)Lin(-) bone marrow cells with IL-7 could acquire cytotoxicity after exposure to additional cytokines and what changes promoted cytotoxicity. The cells cultured with IL-7 already had granzyme B as well as perforin, as previously reported, the proteins of cytotoxic granules. The cells also lacked LFA-1. After 1 wk of secondary culture with either IL-2 or IL-15, but not with IL-12 or IL-18, the IL-7-cultured cells acquired cytotoxicity. IL-2 or IL-15 also induced LFA-1. Ab to the LFA-1 subunits CD11a and CD18 blocked lysis by the NK cells, indicating that the new LFA-1 correlated with, and was essential for, the cytotoxic function of the in vitro generated cells. The LFA-1 also participated in target cell binding by the in vitro differentiated cells. In this study, we demonstrated a new function for IL-15, the induction of LFA-1 in NK progenitor cells, and that IL-15 does more than merely support NK progenitor cell proliferation. The efficacy after only 1 wk of IL-15 administration is a positive practical feature that may apply to human therapy.
Barao
Isabel
I
Department of Microbiology, Veterans Affairs Medical Center, School of Medicine, University of Nevada, Reno, NV 89509, USA.
Hudig
Dorothy
D
Ascensao
Joao L
JL
D000276:Adjuvants, Immunologic / Q000494:pharmacology; D000328:Adult; D018952:Antigens, CD34 / Q000096:biosynthesis*; D001854:Bone Marrow Cells / Q000166:cytology* / Q000201:enzymology / Q000276:immunology*; D002448:Cell Adhesion / Q000276:immunology; D002454:Cell Differentiation / Q000276:immunology; D019070:Cell Lineage / Q000276:immunology; D002478:Cells, Cultured; D003602:Cytotoxicity, Immunologic / Q000276:immunology*; D053804:Granzymes; D006801:Humans; D019409:Interleukin-15 / Q000494:pharmacology*; D007376:Interleukin-2 / Q000494:pharmacology; D015851:Interleukin-7 / Q000494:pharmacology; D020014:K562 Cells; D007694:Killer Cells, Natural / Q000166:cytology* / Q000201:enzymology / Q000276:immunology*; D016169:Lymphocyte Function-Associated Antigen-1 / Q000096:biosynthesis* / Q000502:physiology; D012697:Serine Endopeptidases / Q000096:biosynthesis; D015854:Up-Regulation / Q000276:immunology
D000276:Adjuvants, Immunologic; D018952:Antigens, CD34; D019409:Interleukin-15; D007376:Interleukin-2; D015851:Interleukin-7; D016169:Lymphocyte Function-Associated Antigen-1; C509213:GZMB protein, human; D053804:Granzymes; D012697:Serine Endopeptidases