CD4+ and CD8+ lymphocytes and HIV RNA in HIV infection: high baseline counts and in particular rapid decrease of CD8+ lymphocytes predict AIDS

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Abstract
To study the progression of HIV infection in relation to immunological and virological variables with emphasis on the role of CD8+ lymphocytes. Prospective follow-up from October 1991 of patients observed for at least 18 months allowing nucleoside analogue monotherapy. Peripheral CD4+ and CD8+ lymphocyte counts, HIV RNA, and soluble CD8 were analysed by statistics allowing the evaluation of serial data, avoiding time points with concurrent infections. Tertiary university clinic. Forty-nine patients were followed for 52.6 months, baseline CD4+ count of 300×106/l, sample interval of 5.9 months (medians). AIDS, death, and CDC groups B- or C-related events. AIDS developed in 28% of patients. Baseline CD8+ counts above the median were significantly associated with AIDS development; the best Cox model included CD8+ cells and the log10 RNA/CD4 ratio. A decline in CD8+ counts relative to baseline most significantly predicted AIDS, along with higher baseline RNA and actual CD4+ counts of less than 200×106/l. Levels of soluble CD8 in the blood relative to total CD8+ cells significantly increased in patients developing AIDS. Death occurred in 16% of the patients, and was only predicted by high CD8+ cell counts at baseline. CDC B- and C-related events occurred in 35% of the patients and were best predicted by high baseline CD8+ counts and high RNA levels. The serial quantitation of CD8+ lymphocytes gave highly significant predictive information on the natural progression of HIV infection in patients with moderate to severe immune deficiency. Our data suggest that the hyperactivation of CD8+ lymphocytes is an important factor leading to a numerical decrease of CD8+ lymphocytes in progressive HIV infection.