Using multiple regression modeling we will assess the relationships of TNF, IL-6 vitamin D levels and TBBMC. It is estimated that 50% of the HIV positive children who are screened will meet the inclusion criteria for the trial and that approximately 100 to 120 HIV positive children will be available for the cross sectional comparison and so an equal number of healthy children will be also recruited. With a total of 200 children, the sample size will be large enough to add up to 18 covariates in addition to the grouping factor (HIV-positive versus healthy) and test for a 5% increase in R2, with alpha = 0.05 and power = 80 %. A sample of 100 HIV-positive children alone will allow for a regression analysis that includes up to 9 predictors which collectively explain at least 15% of the variance of the outcome variable (TBBMC, etc.) with alpha = 0.05 and power = 80 %.