[Lymphocyte function of pulmonary tuberculosis in the elderly].

The skin test to tuberculin purified protein derivatives (PPD) was examined in 161 cases of newly diagnosed active pulmonary tuberculosis. Tuberculin reaction was reduced in size with aging, and was significantly lower in the age group of 70 years or over than of less than 50. PPD- or PHA-induced proliferation tests of peripheral blood lymphocytes were examined in vitro, and suppression of lymphocyte proliferative reaction was shown especially on the number of activated T lymphocyte subsets (IL2-R or HLA-DR positive T lymphocytes) in the group of 70 years or over. These findings suggest that the suppression of cellular immunity caused in aged persons is one of the pathogenetic factors for pulmonary tuberculosis.