Daily quality control in CD3+ and CD4+ T cell estimation by the FACSCount system at a tertiary care center in south India.

CD4(+) T cell count estimations are subject to high variations; hence, in this study, the previous day's tested samples were included routinely as the internal quality controls. The percentages of variation of the 2-day values were analyzed for 280 observations and the mean variation for CD4(+) and CD3(+) T cell counts ranged from 5.21% to 9.66%. This method is a good internal quality control (IQC) procedure for the estimation of CD3(+) and CD4(+) T cell counts in resource-poor settings.