Figure A shows mean percent recovery of IL-6 added at final concentrations of 100, 50, 25, 12.5, and 6.25 pg/ml to serum samples of three HIV-negative (solid line) and nine HIV-positive donors (dashed line), as measured by the MSD (left) and CBA (right) kits. Figures B to F show the mean recovery of IL-6, IL-10, IL-8, IL-12p70, TNF-α, and IL-1β among all study participants obtained with the MSD (solid line) and CBA (dashed line) kits, regardless of HIV infection, AIDS, or therapy status (N=12). Horizontal gray lines show the 100 ± 25% acceptance criteria. Error bars show ± 1 standard error of the mean (SEM) of the mean values.