β-carotene supplementation enhances lymphocyte proliferation with mitogens in human peripheral blood lymphocytes

Abstract

This study was performed to determine the effect of β-carotene supplementation on the proliferation of human peripheral blood lymphocytes (PBL) with T-cell mitogens such as phytohemagglutinin (PHA) and concanavalin A (Con A). Subjects were healthy male university students (19 to 22 years old) without smoking habit. After the subjects were divided into two groups; control (n=7) and β-carotene supplemented (n=8) groups, they received lactose (30 mg/day) and β-carotene (30 mg/day) for 30 days, respectively. Their peripheral blood lymphocytes (PBL) were separated by Percoll-density gradient centrifugation and used for immunological assays. The number of PBL from β-carotene supplemented group was not significantly different from control group. Although there was also no significant difference in natural killer cell (NK) activity between both groups (Control; 33.4 ± 8.2%, β-carotene; 32.5 ± 7.7%), proliferation of PBL with PHA or ConA was 1.4 to 1.9 fold higher in β-carotene supplemented group compared to that of control group. However, the proportions of T cell subsets in PBL and interleukin 2 (IL2) activity in the supernatant of PBL cultures stimulated in vitro with Con A were not significant differences between control and β-carotene supplemented groups. In particular, IL2 activity was lower in β-carotene supplemented subjects compared to that of control subjects. These results suggest that the enhancement of PBL proliferation following β-carotene supplementation is not due to the qualitative change in T cell subsets of PBL and the increase in IL2 production as T cell growth factor but due to the enhancement in the responsiveness of PBL to mitogen.