Effect of blood donation on the establishment of normal ranges of lymphocyte subsets

BACKGROUND: Absolute counts of CD4+ T-lymphocytes are used in the management of patients with human immunodeficiency virus infection. Low absolute counts of CD3+CD4+ cells have also been observed in healthy people–a phenomenon called idiopathic CD4 lymphocytopenia. It is common practice for normal ranges for lymphocyte subsets to be derived from samples taken from blood donors. STUDY DESIGN AND METHODS: A sample of EDTA blood was taken through the donation line tubing, after donation from 565 blood donors in Sydney, Australia, who were selected from a range of age groups. An additional 12 donors provided a predonation sample as well as a postdonation sample. Hematologic assays were performed on two analyzers. Samples were stained for CD3, CD4, CD8, CD19, and CD56 and analyzed on a flow cytometer. RESULTS: Three donors were found to have absolute CD3+CD4+ counts < 300 cells per microL. The percentage of CD3+CD4+ cells was found to increase with age. Both the percentage and the absolute count of CD3+CD8+ cells decreased with age, which resulted in an increased CD4:CD8 ratio with age. Men had consistently higher absolute counts of CD3-CD56+ cells than women. The 12 additional donors all had greater percentages of CD3+CD4+ cells and lower absolute counts for CD3+, CD3+CD4+, CD3+CD8+, CD19+ and CD3-CD56+ cells after donation than they had before donation (p < 0.001). CONCLUSION: It is not satisfactory to base normal ranges for lymphocyte subsets on donor blood, from which the blood sample has been obtained after donation.