Cell-mediated immunity in an ageing population.
Eight hundred and eighty patients hospitalized in a geriatric hospital were routinely tested with 2, 10, 30 and 100 i.u. tuberculin. Among these, fifty-four patients were selected on the basis of negative skin tests and absence of evident diseases interfering with the function of the immune apparatus. A battery of tests analysing cell-mediated immunity was applied to those fifty-four patients. It appears that elderly patients having a negative test to 100 i.u. tuberculin show very infrequent sensitization to three other thymus-dependent antigens. The capacity of this selected population to become sensitized to DNCB is poor (20%). Furthermore they exhibit a low per cent of peripheral blood T cells (36%) and a poor capacity to respond in vitro to mitogens such as PHA. Testing the in vitro response to a battery of antigens demonstrates a good correlation with the results of the skin tests. Finally the leucocytes of 25% of this selected population failed to produce LIF in vitro in the presence of PHA. These results suggest not only an absolute decrease in the population of circulating T lymphocytes in those elderly humans; but very likely, at least in some cases, a functional impairment of T cells.
D000328:Adult; D000368:Aged; D000375:Aging; D004137:Dinitrochlorobenzene / Q000276:immunology; D006801:Humans; D007111:Immunity, Cellular; D007136:Immunoglobulins / Q000032:analysis; D007958:Leukocyte Count; D008213:Lymphocyte Activation; D008214:Lymphocytes; D008263:Macrophage Migration-Inhibitory Factors / Q000032:analysis; D008875:Middle Aged; D012882:Skin Tests
D004137:Dinitrochlorobenzene; D007136:Immunoglobulins; D008263:Macrophage Migration-Inhibitory Factors