Selective decline in cellular immune response to varicella-zoster in the elderly.

The incidence of herpes zoster rises markedly in the aged. We evaluated the hypothesis that cellular immunity to varicella-zoster (VZ) viral antigens may be impaired in aged subjects. We found that the lymphocyte proliferation to VZ antigen was less in older asymptomatic individuals than in normal young controls. In contrast, responses to other antigens did not differ. Antibody titers to VZ were similar in both young and old subjects. Impairment of cellular immunity to VZ, on a population basis, may contribute to the increased risk of herpes zoster in the elderly.