CYTOIMMUNOLOGICAL ABNORMALITIES IN CEREBROSPINAL-FLUID IN EARLY STAGES OF HIV-1 INFECTION OFTEN PRECEDE CHANGES IN BLOOD

We determined the proportions of CD2+, CD4+ and CD8+ lymphocytes in the cerebrospinal fluid (CSF) and paired blood samples of 19 neurologically examined subjects with CDC II/III stage HIV-1 infection and 21 controls. Using a three-layer indirect immunoperoxidase technique, we found that 16 HIV-1-infected subjects had an abnormally low CD4+/CD8+ ratio of the CSF due to a decrease in the proportion of CD4+ T cells and/or an increase in that of CD8+ lymphocytes. Compared to controls, in the HIV-1-infected group this ratio appeared to be lower in both CSF and blood (P < 0.001). The changes of lymphocyte subpopulations were more marked in the CSF than in blood, and no clear associations were found between the findings of paired CSF and blood samples. Cytological examination of the CSF revealed that 12 of 14 patients had an elevated total cell count and an abnormal differential count with a predominance of mononuclear phagocytes. An elevated number and/or proportion of enlarged lymphoid cells was found in most cases. The total cell counts, and total numbers of mononuclear phagocytes and lymphocytes of the patients were higher than in controls (P < 0.001). Our study shows that the changes in CSF lymphocyte subsets often precede those in blood and that immunological events in the central nervous system (CNS) are not directly reflected in peripheral blood. Cytoimmunological abnormalities in the CSF of individuals with early stages of HIV-1 infection indicate subclinical CNS involvement, and may be of importance for therapeutic considerations.