Acute tubulointerstitial nephritis with an autoantibody response against carbonic anhydrase II.

An autoantibody against carbonic anhydrase II was identified in a case of acute tubulointerstitial nephritis induced by famotidine, which inhibits carbonic anhydrase II in addition to the gastric proton pump. The patient's serum reacted with distal nephron homogenates at the same molecular weight as purified carbonic anhydrase II, and immunohistochemistry using the patient's serum showed staining at the distal nephron. Carbonic anhydrase II may be a causative antigen in the famotidine-induced acute tubulointerstitial nephritis.