CD34+-enriched peripheral blood progenitor cells from unrelated donors for allografting of adult patients: high risk of graft failure, infection and relapse despite donor lymphocyte add-back.

Fifty-one adults with haematological malignancies were transplanted with CD34+-selected peripheral blood progenitor cells (PBPC) from unrelated donors. The conditioning protocol contained total body irradiation (n = 17) or combinations of busulphan and other alkylating agents (n = 34). Antithymocyte globulin was infused in all patients. The median number of CD3+ T cells infused with the graft after purification with the Isolex 300 system in the first cohort of 18 patients was 2.1 x 10(5)/kg. Prophylactic donor lymphocyte infusion (DLI) containing 1 x 10(5) CD3+ T cells was performed on d 21 in the following 33 patients who had received PBPC purified by the CliniMACS system. Early graft failure occurred in 8/51 patients (16%). After a median follow-up of 31 months (range 8-60), the probability of disease-free survival (DFS) was 36% for the whole group. Reasons for death were opportunistic infections (n = 15), graft-versus-host disease (GvHD, n = 7) and relapse (n = 4). Pre-transplant factors with significant impact on DFS were cytomegalovirus status and risk category of underlying disease. The occurrence of graft failure or GvHD was associated with poor outcome. Recipients of CD34+-selected PBPC from unrelated donors are at high risk of infectious complications, relapse and graft failure which cannot be prevented by early reinfusion of unmodified donor lymphocytes.