title: Natural killer cell cytotoxicity is not regulated by folic acid in vitro.
abstract: OBJECTIVE
  Folate supplementation may be associated with an increased risk of developing several types of cancer and a derangement of immune function. Among the latter, Natural killer (NK) cells are involved in non-MHC-restricted natural immunity against malignant target cells. Abnormalities in NK cell number or function have been associated with a higher cancer risk. The aim of this study was to study in vitro the possible effect of different concentrations of 5-methyltetrahydrofolic acid (5-MTHF) or folic acid on NK cell cytotoxic function, and expression of the stimulatory and inhibitory receptors KIRDL4, KIRDL3, and NKG2D.
  
  
  METHODS
  Volunteer-derived peripheral mononuclear cells (PBMC) and highly enriched NK cells (95% CD56+ CD16+) were grown in folic acid free-RPMI 1640, supplemented either with folic acid or 5-MTHF (15-100 nM) during 72 h to 96 h.
  
  
  RESULTS
  No differences in the cytolytic activity of PBMC and enriched NK cells were observed. After 96 h of in vitro culture without folate or supplemented with FA or 5-MTHF (30 or 100 nM), there were no changes in the percentage of HPNK receptor-positive cells.
  
  
  CONCLUSIONS
  Our data indicate that a high dose of 5-MTHF or folic acid does not influence NK cell function in vitro.
authors: Institute of Nutrition and Food Technology (INTA), University of Chile, Santiago, Chile. shirsch@inta.uchile.cl
authors: Sandra
authors: S
authors: Hirsch
authors: Dante
authors: D
authors: Miranda
authors: Estefanía
authors: E
authors: Muñoz
authors: Margarita
authors: M
authors: Montoya
authors: Ana María
authors: AM
authors: Ronco
authors: María Pía
authors: MP
authors: de la Maza
authors: Daniel
authors: D
authors: Bunout
mesh_terms: D019002:CD56 Antigen / Q000378:metabolism; D003602:Cytotoxicity, Immunologic / Q000187:drug effects*; D019587:Dietary Supplements; D005260:Female; D005492:Folic Acid / Q000276:immunology / Q000378:metabolism / Q000494:pharmacology*; D006801:Humans; D007694:Killer Cells, Natural / Q000276:immunology* / Q000378:metabolism; D007963:Leukocytes, Mononuclear / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism; D008297:Male; D009369:Neoplasms / Q000276:immunology* / Q000378:metabolism; D017452:Receptors, IgG / Q000378:metabolism; D055607:Receptors, Natural Killer Cell / Q000378:metabolism*; D013763:Tetrahydrofolates / Q000276:immunology / Q000378:metabolism / Q000494:pharmacology; D014803:Vitamin B Complex / Q000276:immunology / Q000378:metabolism / Q000494:pharmacology*
chemical_list: D019002:CD56 Antigen; D017452:Receptors, IgG; D055607:Receptors, Natural Killer Cell; D013763:Tetrahydrofolates; D014803:Vitamin B Complex; D005492:Folic Acid; C005984:5-methyltetrahydrofolate