CD4+ T-lymphocyte variations in patients with advanced human immunodeficiency virus infection and counts below 100...

Variability in CD4+ T-lymphocyte measurements has been described for both normal and human immunodeficiency virus (HIV)-infected persons. Clinical protocols use CD4+ cell counts as surrogate markers for disease progression or response. In this study, we determined the variability of CD4+ T-lymphocytes below 100 cells/microl when measured less than 7 days apart. Two consecutive lymphocyte subset measurements were performed in 55 patients using CD3/CD4 antibodies in a flow cytometer (Epics Profile II). Specimens were collected between 8:00 and 10:00 am within the same week. Data from the first and second measurements were compared. The average total lymphocyte count on the first measurement was 1,064 (360-2,853), and on the second 1,162 (320-2,223; P = 0.07); the percentage CD4 was 1.76 (0-8) on the first, and on the second 1.98 (0-9; P = 0.3); the absolute CD4 cell count on the first measurement was 16.6 (0-57) and on the second 22.8 (0-93; P = 0.01). Statistically significant differences were found between the first and second absolute CD4 T-lymphocytes but not in the CD4 percentage. These differences probably are due to variations in total lymphocyte count. For research protocols, repeating CD4+ cell determinations within a short period is advisable, to ensure a homogeneous population. On the other hand, for day-to-day patient follow-up, a combination of clinical criteria and both percentage and absolute CD4+ cell counts should be used to make treatment decisions, because repeating CD4 cell measurements can be very costly.