A boy with IgA nephropathy complicated by tubulointerstitial nephritis and uveitis (TINU) syndrome

Abnormal cellular and humoral immunity underlie both immunoglobulin A (IgA) nephropathy and tubulointerstitial nephritis and uveitis (TINU) syndrome. We encountered a teenage boy who developed TINU syndrome during the course of IgA nephropathy.

1 year after onset of IgA nephropathy following acute enteritis, a 14-year-old boy again experienced acute enteritis caused by Campylobacter jejuni, which was followed by TINU syndrome with prominent low-molecular-weight proteinuria. Renal histologic examination showed T-cell-dominant tubulointerstitial infiltration of marked immune cells including CD54-positive cells. Steroid therapy improved renal function, reversing aggravation of IgA nephropathy by TINU syndrome.

The boy's human leukocyte antigen profile suggested predisposition to these two diseases, triggered by which were intestinal infections. The enteritis probably induced abnormalities in cellular and humoral immunity. Low-molecular-weight proteinuria, which reflected our patient's tubulointerstitial lesions, should call for consideration of TINU syndrome, including ophthalmologic assessment for possible uveitis.