Natural killer cell lytic activity

Figure 1. Effects of an 8-day dietary repletion with all-fran -retinoic acid or retinol (ROH) on natural killer (NK) cell cytotoxicity in rats previously deficient in vitamin A (VA). Values are means SE of NK cell cytolytic activity (lytic units) per 10 NK cells (anti-NKR-Pl A" cells by flow cytometry). At the beginning of the repletion period, groups of five VA-deficient and five VA-sufficient rats were killed to confirm the low splenic NK cell activity of VA-deficient rats. Other VA-deficient animals were switched at this time to the RA-containing diet or to the retinol-sufficient diet. Eight days later, splenic NK cell cytotoxic activity and NK cell number were examined in four VA-deficient and five RA- and five ROH-repleted rats. Significantly different (P < 0.05) from VA-deficient rats. Significantly different (P < 0.05) from VA-deficient and VA-sufificient rats (Mann-Whitney U test). From reference [48] with permission.

HPR has been shown to influnce the immune system. In vitamin A-deficient rats, 4HPR increased the number of lymphocytes and natural killer (NK) cells and it slightly increased NK cell lytic efficiency [65]. In breast cancer patients treated for six months with 200 mg 4HPR, the NK activity was augmented by 73% as compared to that of control patients [66] (Tab. 3). 

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