Lymphocyte responses to varicella zoster virus in the elderly

Elderly subjects (age 75-95 years) immune to varicella zoster virus (VZV) were identified by the presence of serum IgG antibody. The frequency of lymphocytes in their blood which proliferated in varicella zoster virus antigen-stimulated cultures was 1:78,000 +/- 6600. This is less than the 1:14,000 +/- 2000 frequency of VZV-responsive lymphocytes in blood from younger adult (20-43 years) donors. Elderly donors' blood mononuclear cells were less efficient than those of younger adults at lysing VZV-infected fibroblasts but not K562 target cells. The lysis of VZV target cells by elderly donors' MNC increased to control levels in the presence of 10 U/ml of interleukin-2 (IL-2). These results suggest that mononuclear cells capable of killing VZV-infected target cells persist with aging but that reduced numbers of antigen-responsive and lymphokine-releasing T cells may limit their function.