Acute interstitial nephritis with predominant plasmacytic infiltration in patients with HIV-1 infection.

We describe a new form of acute interstitial nephritis with predominant plasmacytic infiltration in 2 patients with active human immunodeficiency virus 1 (HIV-1) infection. Clinical features included acute kidney injury and proteinuria, but no sicca syndrome. Acute kidney injury was characterized by a high serum creatinine level and nephrotic syndrome with no hematuria or leukocyturia. Kidney biopsy specimens from both patients showed interstitial infiltration by mononuclear cells composed mainly of CD138(+) plasmacytes and diffuse effacement of podocyte foot processes with no deposits. In one patient with Guillain-Barré syndrome, a sural nerve biopsy showed plasmacyte infiltration and immunohistochemistry was strongly positive for HIV-1 p24 protein. In both patients, minor salivary glands and bone marrow were infiltrated by lymphocytes, consistent with B-cell activation induced by HIV-1 infection. Other common causes of acute interstitial nephritis, including B-cell lymphoma and diffuse infiltrative lymphocytosis syndrome, were actively looked for and excluded. Treatment with highly active antiretroviral therapy was effective; symptoms rapidly improved, serum creatinine level decreased, and proteinuria resolved. Exclusion of other common known causes of acute interstitial nephritis and the dramatic response with highly active antiretroviral therapy suggests HIV-1 as a likely cause. The acute interstitial nephritis probably was induced by HIV-1-driven nonspecific B-cell activation. Further investigations are needed to confirm the direct pathogenic role of HIV-1.