The characterization of non-progressors: long-term HIV-1 infection with stable CD4+ T-cell levels

Abstract

Objective: To identify and characterize individuals with long-term HIV-1 infection who have experienced little or no progressive CD4+ T-cell loss during follow-up.

Patients and methods: The rate of CD4+ T-cell loss (CD4 slope) was determined for each of the 290 participants in the San Francisco Men's Health Study who were seropositive at study entry in 1984. The study population was stratified, by CD4 slope, into 10 groups of 29 individuals and each group was characterized using a variety of cross-sectional and longitudinal laboratory measurements.

Results: Approximately 10% of the HIV-1-infected men experienced no net CD4+ T-cell loss during 78 months of follow-up. Compared with all other seropositive subjects, these 'non-progressors' were the extreme cases in a relatively continuous distribution of CD4 slopes, rather than a discrete subpopulation. Although they had no net cell loss, their mean CD4+ cell count was approximately 400 x 10(6)/l lower and their mean CD8+ cell count approximately 250 x 10(6)/l higher than seronegative subjects, suggesting early changes followed by stabilization. The CD4 slope was associated with the levels of beta 2-microglobulin, neopterin, p24 antibody, erythrocyte sedimentation rate, viral burden, and the proportion of HIV-1 isolates with tropism for the MT-2 T-cell line. Multivariate cluster analysis of these laboratory markers did not distinguish the non-progressors as a distinct subgroup.

Conclusions: These findings support both a biphasic natural history and the suggestion that the broad range in HIV disease progression rates may be the result of several independent factors interacting in a variety of combinations. Recent changes in laboratory markers, known to predict both CD4+ cell loss and AIDS, suggest that non-progressors are undergoing slow HIV disease progression.