Natural killer cell mediated cytotoxicity of tumor cells initiated by neem leaf preparation is associated with CD40-CD40L-mediated endogenous production of interleukin-12.
Neem leaf preparation (NLP) was found to activate natural killer (NK) cells (CD56(+)CD3(-)) to enhance their cytotoxic ability to tumor cells and stimulate the release of interleukin-12 (IL-12) from macrophages from healthy individuals and head-and-neck squamous cell carcinoma patients. NLP upregulated cytotoxic (CD16(+) and CD56(dim)) NK cells, and the cytotoxicity of NK-sensitive K562 cells by NLP-stimulated peripheral blood mononuclear cells decreased significantly after IL-12 neutralization. This NK-mediated cytotoxicity was manifest by upregulation of IL-12-dependent intracellular expression of the perforin-granzyme B system. Moreover, NK cytotoxic function was abolished after use of concanamycin A, a perforin inhibitor, but not by brefeldin A, a Fas inhibitor, confirming the participation of the perforin-granzyme B system. In addition NLP upregulated the expression of CD40 in CD14(+) monocytes and CD40L in CD56(+) lymphocytes. Neutralization of CD40 and CD40L in NLP-stimulated peripheral blood mononuclear cells culture resulted in significant downregulation of IL-12 release and cytotoxicity of NK cells, demonstrating the role of a CD40-CD40L interaction in the observed functions. Signals involved in the NLP-induced release of IL-12, and thereby induction of NK cell cytotoxicity, are mediated by activating p38MAPK pathway, but not through the ERK1/2 signaling pathway. Overall the results suggest that NLP effects NK cellular cytotoxicity by CD40-CD40L-mediated endogenous production of IL-12, which critically controls perforin-dependent tumor cell cytotoxicity.
Bose
Anamika
A
Department of Immunoregulation and Immunodiagnostics, Chittaranjan National Cancer Institute, Kolkata, India.
Baral
Rathindranath
R
D000328:Adult; D031601:Azadirachta / Q000737:chemistry; D019013:CD40 Antigens / Q000378:metabolism; D023201:CD40 Ligand / Q000378:metabolism; D019002:CD56 Antigen / Q000096:biosynthesis; D002294:Carcinoma, Squamous Cell / Q000188:drug therapy*; D002452:Cell Count; D045744:Cell Line, Tumor; D003602:Cytotoxicity, Immunologic / Q000187:drug effects*; D005260:Female; D006258:Head and Neck Neoplasms / Q000188:drug therapy*; D006801:Humans; D018664:Interleukin-12 / Q000378:metabolism*; D007694:Killer Cells, Natural / Q000187:drug effects / Q000276:immunology*; D007963:Leukocytes, Mononuclear / Q000276:immunology; D020935:MAP Kinase Signaling System / Q000187:drug effects; D008297:Male; D008875:Middle Aged; D008517:Phytotherapy; D018515:Plant Leaves / Q000737:chemistry; D028321:Plant Preparations / Q000494:pharmacology; D015854:Up-Regulation / Q000187:drug effects / Q000276:immunology
D019013:CD40 Antigens; D019002:CD56 Antigen; D028321:Plant Preparations; D023201:CD40 Ligand; D018664:Interleukin-12