Acute interstitial nephritis: immunologic and clinical aspects.

Acute interstitial nephritis is a common renal syndrome that may be associated with a variety of infections and drug therapies or may develop without an identified cause. Three cases are presented to illustrate the three types of acute interstitial nephritis--drug related, infection related, and idiopathic. Cell-mediated immune mechanisms seem to be more important than humorally mediated mechanisms in the pathogenesis of acute interstitial nephritis. Frequently, eosinophils are identified as a component of the interstitial cellular infiltrate, and eosinophiluria and eosinophilia have been claimed to be helpful in the diagnosis of acute interstitial nephritis, especially the drug-induced type. Neither eosinophiluria nor the presence of increased urinary levels of eosinophil major basic protein, however, is specific for the diagnosis of acute interstitial nephritis. Patients with drug-induced interstitial nephritis frequently have symptoms and signs suggestive of a hypersensitivity syndrome and rarely have more dramatic anaphylactic manifestations. Systemic glucocorticoids have been shown to be beneficial in this type of acute interstitial nephritis.