Assessment of hematological and immunological function during long-term follow-up after peripheral blood stem cell transplantation

Abstract

BACKGROUND AND OBJECTIVE: Long-term hemopoietic and immunological profile after autologous peripheral blood progenitor cells transplantation (PBPCT), in patients affected by hematological malignancies is largely unknown. The aim of this work was to detect the impact of high dose chemotherapy and PBPCT on hemopoietic and immunological function compared to conventional chemotherapy. DESIGN AND METHODS: Patients had to fulfill the following criteria: continuous complete remission after PBPCT, follow-up longer than 12 months, no chemo or radiotherapy or biological response modifiers after PBPCT. Twenty-five patients were considered eligible for this analysis. Stable and complete hemopoietic reconstitution (Hb > 12 g/dL, WB > 4.0 x 10(9)/L, ANC > 1.5 x 10(9)/L and Pits count > 150 x 10(9)/L), morphological examination of peripheral blood and bone marrow, cytogenetic analysis and immunological profile were evaluated at 12 months and yearly thereafter. RESULTS: Immunological reconstitution showed a persistent reduction of CD4/CD8 ratio up to five years after PBPCT. This reduction was related to a persistent increase of CD8+ lymphocytes and a constant reduction of CD4+ lymphocytes. INTERPRETATION AND CONCLUSIONS: Defects observed in PBPCT patients are induced by the procedure itself, by the conditioning regimen or both. The different behavior in the immune reconstitution of CD8+ subset after PBPCT may be favored by an extrathymic origin of these cells while CD4+ subset recovery which is thymus-dependent is impaired after PBPCT in adult population. Long-term hemopoietic reconstitution after PBPCT is rapidly obtained and is stable over the years, long-term immunological function seems to be abnormal in these patients and these abnormalities are long-lasting.