Enriching T cells from PBMCs results in a substantially improved stimulatory response to anti-CD3, evident by an increased proliferative response and improved up-regulation of CD69 by CD4⁺ T cells and CD4⁺CD45RA⁺ cells.

PBMCs and highly enriched T cells (see “Patients, materials, and methods”) of control samples and patient samples were stimulated with immobilized anti-CD3 comparing (A) the proliferative response measured by [³H]thymidine uptake (1.0 × 10⁵cells/well) (left panel); blank bars, control cells; black bars, patient cells; the bars represent the cpm (mean ± SEM) of triplicate cultures; (B) the capacity to up-regulate CD69 after 24 hours of culture (right panels). CD4⁺ T cells were identified by anti-CD4 and gated and assessed for expression of CD45RA. The density of expression of CD69 was estimated by the mpc in histogram plots. Thin line indicates control cells; thick line, patient cells. Samples were obtained from an 8-year-old boy with thalassemia major (patient 22) 6 months after allo-BMT. CD4⁺CD45RA⁺ cells, 138/μL.