治療後ウエスタンブロット法にて抗HIV 抗体が陰性化し 持続しているHIV-1 感染症の1 例

Abstract

Western blot (WB) is the most widely accepted confirmatory assay for detecting antibodies to the human immunodeficiency virus 1 (HIV-1). We report the case of an HIV-1 patient whose WB was negative for over two years. A 41-year-old Japanese man with Pneumocystis pneumonia (PCP) and pulmonary tuberculosis referred in March 2005 was found to have positive HIV-1 ELISA and HIV RNA PCR, but HIV-1 WB with only two bands, at gp160 and p18, and no WB HIV-2 band. The CD4 count was 37/microL, and total immunoglobulin, IgG, IgM, and IgG subclasses were normal. The man was treated for PCP and pulmonary tuberculosis, then underwent antiretroviral therapy. He had taken short-terms steroids to treat a drug allergy and immune reconstitution syndrome. Six months later, his serological ELISA tests for HIV-1 and HIV DNA PCR were negative and WB showed no positive band. The CD4 count recovered gradually, and exceeded 350/microL two years later, but WB remained negative. Lymphoproliferative assays and interferon y expression against HIV-pl7, p24, and p41 were studied and compared to those of other HIV-1 infected patients. Our patient showed no response to p17 or p24 and only a weak response to p41. Other patients showed a response to HIV-antigens, but patients with antiretroviral therapy or with histories of steroid use responded more weakly than those with neither. These findings show that HIV-specific lymphocytes decline with antiretroviral therapy and steroid treatment within early HIV infection. It is therefore important to interpret negative serological tests carefully in patients such as ours.