A reduced lymphoproliferative response of PBMCs in the post–T-cell depletion period results from a reduced proliferative capacity of T cells.

To exclude that after T-cell–depleting therapy depressed lymphoproliferative responses of PBMCs simply reflect a reduced number of proliferating T cells, the proliferative responses to stimulation with immobilized anti-CD3 of 1 × 10⁵ PBMCs were compared with that of an enriched T-cell population (7.5 × 10⁴) recombined with enriched monocytes (2.5 × 10⁴). Blank bars, control cells; black bars, patient cells. The bars represent the cpm (mean ± SEM) of triplicate cultures. Patient cells were obtained from an 8-year-old boy with ALL (patient 17) 3 months after matched unrelated donor (MUD)–BMT.