Effect of zinc supplementation on cell-mediated immunity and lymphocyte subsets in preschool children.

OBJECTIVE In a zinc supplementation trial (with a significant impact on diarrheal morbidity), to evaluate effect of zinc supplementation on cellular immune status before and after 120 days of supplementation. DESIGN A double blind, randomized controlled trial with immune assessment at baseline and after 120 days on supplement. SETTING Community based study in an urban slum population. SUBJECTS Randomly selected children (zinc 38, control 48), had a Multitest CMI skin test at both times. In 66 children (zinc 22, control 34), proportions of CD3, CD4, CD8, CD16, CD20 cells and the CD/CD8 ratio were also estimated using a whole blood lysis method and flowcytometry. INTERVENTION Zinc gluconate to provide elemental zinc 10 mg daily and 20 mg during diarrhea. MAIN OUTCOME RESULTS Regarding CMI, the percentage of anergic or hypoergic children (using induration score) decreased from 67% to 47% in the zinc group, while in the control group it remained unchanged (73% vs 71%) (p = 0.05). The percentage of children deteriorating between first and second tests was significantly lower in the zinc group (13% vs 33%, p = 0.03). Regarding lymphocyte subsets, the zinc group had a significantly higher rise in the geometric means of CD3 (25%, p = 0.02), CD4 (64% p = 0.001), and CD4/CD8 ratio (73% p = 0.004) with no difference in CD8 and CD20. The rise in CD4 was significantly higher in the zinc as compared to the control group; the ratio of geometric means was 1.45 (95% CI, 1.03-2.01). CONCLUSION Zinc supplementation improves cellular immune status, which may have been one of the mechanisms for observed impact of zinc supplementation on diarrheal morbidity.