Results of 93 CD4 T cell count measurements from children aged less than 5 years and more than 18 months in the suburb of Yaoundé, expressed in absolute number (cells/μl) and in percentage carried out in parallel by the Auto40 flow cytometer and by FACSCalibur. - A and C. Passing-Bablok agreement test between the CD4 T cell count results obtained with the Auto40 and FACSCalibur flow cytometers, in absolute number (A) and in percentage (C). The diagonal dotted line represents the ideal line (no bias). The full line represents the regression line of the distribution; - B and D. Bland-Altman analysis on the relative differences between the CD4 T cell counts obtained with the Auto40 and FACSCalibur flow cytometers compared with the average CD4 T cell count, in absolute number (B) and in percentage (C). The full line represents the mean relative difference, and the dotted lines represent the superior and inferior limits of agreement. The arrow corresponds to the X abscise axis.