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Updated: May 15, 2026

A Flow Cytometry-Based Cytotoxicity Assay for the Assessment of Human NK Cell Activity
Published on: August 9, 2017
Natural killer cell cytotoxicity is not regulated by folic acid in vitro
Sandra Hirsch1, Dante Miranda, Estefanía Muñoz
1Institute of Nutrition and Food Technology (INTA), University of Chile, Santiago, Chile. shirsch@inta.uchile.cl
Objectives:
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.
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