Zinc and immunocompetence in the elderly: Baseline data on zinc nutriture and immunity in unsupplemented subjects

Zinc nutriture and immune function were studied in 100 subjects, age 60-89 yr. Mean (± SD) zinc concentrations found were 84.8 ± 15.5 μg/dL (13.0 ± 2.4 μM) for plasma, 1.04 ± 0.24 μg (0.016 ± 0.004 μmol)/10⁹ cells for erythrocytes, 4.06 ± 1.85 μg (0.062 ± 0.028 μmol)/10⁹ cells for mononuclear cells, 3.91 ± 1.77 μg (0.060 ± 0.027 μmol)/10⁹ cells for polymorphonuclear leukocytes, 0.53 ± 0.39 μg (0.0081 ± 0.0060 μmol)/10⁹ cells for platelets, and 222 ± 101 μg (3.39 ± 1.54 μmol)/g for hair. Zinc ingestion was below the RDA in more than 90% of study subjects. The incidence of anergy to a panel of seven skin test antigens was 41%; responses to these antigens were significantly associated with the plasma zinc concentration. Subjects with depressed lymphocyte responses to mitogens had significantly lower platelet and significantly higher mononuclear cell zinc concentrations than those with normal responses.