A Single 210-μmol Oral Dose of Retinol Does Not Enhance the Immune Response in Children with Measles 1 2

This trial assessed the effect of vitamin A on reversing measles-induced unresponsiveness to recall antigens and on enhancing measles antibody production. These assessments were part of a randomized, doublemasked clinical trial of the efficacy of 210 µmol of retinol as retinyl palmitate for reducing measles-associated morbidity. Two hundred children between 5 mo and 17 y of age with acute measles were enrolled at the Urban Health Centers in Ndola, Zambia; 110 subjects received a placebo and 90 received vitamin A. At enrollment and 2 wk later, blood samples were collected to determine measles hemagglutinin antibody titer and, at 1 and 2 wk post-enrollment, cutaneous delayed-type hypersensitivity tests (DTH) for seven antigens were applied. Both groups of subjects showed marked DTH unrespon siveness, but vitamin A-treated subjects had a significant prolongation of unresponsiveness to tuberculin [odds ratio (OR) 3.22 and 95% confidence interval (CI) 1.27–8.2], Candida (OR 5.43, CI 1.13–25.9) and Proteus (OR 5.17, CI 1.14–28.4), after adjustment for previous vaccination and age. DTH unresponsiveness was antigen specific, reflecting prior vaccination history, and was not associated with acute respiratory infection status. In addition, children in both treatment groups showed a significant increase in measles antibody titer from baseline to wk 2, but this increment was not significantly different between the groups ( P = 0.25). These results indicate that a single oral dose of 210 µmol of retinol as retinyl palmitate in oil does not enhance the immune system during measles.