Immunopathological analysis of interstitial renal lesions in elderly people.

The incidence of focal lymphoid infiltrates in the renal interstitium was examined in autopsy cases of young and old subjects, and the infiltrating lymphocytes were immunohistologically characterized by a panel of monoclonal antibodies. Histologically, 198 and 227 autopsy cases over 60 years of age (87.2%) were shown to have mononuclear cell infiltrates of varying degree in the renal interstitium, whether or not these were accompanied by progressive arteriosclerotic changes. Above all, severely infiltrating foci in the renal interstitium were frequently found in the elderly over 70 years of age overlapping arterio-artherolosclerotic changes. In contrast, in the 54 younger control subjects under 49 years of age, the incidence of such a lesion was less (5.6%). An immunohistologic study revealed that the infiltrating mononuclear cells were predominantly composed of CD4+ cells, whereas CD22+ B cells were apparently lesser in number. Moreover, a considerable proportion of T cells was activated as judged by IL-2 receptor expression. From these findings, we now propose that susceptibility to the development of interstitial renal lesions in the elderly involves the cellular immune response, and may be related to an age-associated disturbance in regulatory T-cell function.