Malnutrition and Variability in CD4+Cell Counts in African Populations

Abstract

Williams et al. investigated a mathematical model to predict the distribution of CD4+ cell counts among HIV-positive adults by use of the distribution among HIV-negative adults in African populations. The study was mainly based on data collected in South Africa and Zambia. The authors noted that CD4+ cell counts vary widely within and among populations. The CD4+ cell count distributions among HIV-negative people had a higher mean in South Africa than in Zambia but the mean rate of decrease in CD4+ cell count among HIV-positive people was higher in South Africa and mean survival was shorter in South Africa than in Zambia at a given CD4+ cell count. The authors did not provide an explanation for these observations which are important for the prediction of mortality at a given CD4+ cell count. Predictions of disease progression and mortality inform the decision-making process about the commencement of antiretroviral treatment in an individual HIV-infected patient. The authors findings could be explained by the impact of nutritional status on CD4+ cell counts. In malnutrition the thymus gland undergoes severe atrophy due to apoptosis-induced thymocyte depletion particularly affecting the immature CD4+ cells as well as a decrease in cell proliferation. This process has been linked to decreased leptin and increased glucocorticoid levels in malnutrition. CD4+ cell counts were found to be lower in children with nonedematous malnutrition than in those with edematous malnutrition. (excerpt)