Immunohistochemical identification of infiltrating mononuclear cells in tubulointerstitial nephritis associated with Sjögren's syndrome.

Using monoclonal antibodies, immunoperoxidase analysis was performed on eight renal biopsy samples obtained from patients with Sjögren's syndrome-associated tubulointerstitial nephritis. In all cases the interstitial infiltrates were predominantly CD5-positive T-cells (mean 66%), whereas both B-cell (CD19-positive) and monocyte (CD15-positive) populations participated to a lesser degree. CD16-positive NK/K cells were rarely encountered. The CD4/CD8 ratio was consistently higher than 1.0 (mean 2.08). The lymphocytes which invaded the tubular epithelial cells to present a feature of tubulitis were CD8-positive, suggesting that they were cytotoxic T-cells. These results were in general accord with those obtained in the salivary glands of patients with Sjögren's syndrome. It was thus concluded that the same immunological process was probably operative in the renal tubulointerstitial tissue as in the salivary glands to induce the characteristic tissue changes of Sjögren's syndrome.