HIV-related neuropsychological impairment and immunodeficiency. CD8+ lymphocytes and neopterin are related to HIV-encephalopathy.

The relationship between neuropsychological test performance and immunological parameters was studied in 52 HIV-positive patients within different stages of the infection. All subjects were neuropsychologically tested, the CD4+ and CD8+ lymphocyte count were measured in peripheral blood, and the concentration of neopterin and HIV-p24 antigen were measured in serum. Ten patients with AIDS were defined as neuropsychologically impaired. The CD8+ cell count was the only immunological parameter that could significantly discriminate between AIDS patients with and without neuropsychological impairment. For the total group, significant positive correlations were found between neuropsychological test results and the number of CD8+ and CD4+ lymphocytes, and significant negative correlations were observed between serum concentration of neopterin and neurocognitive function. Regression analyses showed that up to 51% of the variance in test performance could be explained by CD8+ cells and neopterin concentration. The possible role of CD8+ lymphocytes and neopterin in the pathogenesis of HIV-related CNS-dysfunction is discussed.