Expansion of CD4+CD7- T cells, a memory subset with preferential interleukin-4 production, after bone marrow transplantation.

BACKGROUND: Inadequate reconstitution of CD4+ lymphocyte and interleukin (IL)-2 production defect are observed after bone marrow or peripheral blood stem cell transplantation (SCT). METHODS: We studied immune reconstitution after SCT in 33 consecutive patients who received allogeneic SCT (17 patients) or autologous SCT (16 patients). The aims were to assess the regeneration of the CD4+ T-cell subset with regard to helper cell differentiation. CD4+ T-cell subset regeneration and expansion of the CD4+CD7- subset were studied by immunofluorescence analysis. CD4+CD7- cell cytokine secretion was analyzed after cell sorting and costimulation of the CD3 and CD28 pathways, in enzyme-linked immunosorbent assay and reverse transcription-polymerase chain reaction assays. RESULTS: We report a relative expansion of the CD4+CD7- subset within CD4+ T cells, detected as early as 1 month after bone marrow transplantation and decreasing after day 60. CD4+CD7- T cells preferentially expressed CD45RO and activation markers such as CD57, CD25, and HLA-DR. No relationship was observed between the CD4+CD7- expansion and transplant-related complications. We observed no significant IL-2 production in supernatants from sorted CD4+CD7- T cells, whereas IL-4 levels were comparable to those produced by cells from normal individuals. Autologous CD4+CD7+ cells showed little, if any, IL-4 production, and IL-2 production was lower than that by normal CD4+CD7+ T cells. Reverse transcription-polymerase chain reaction assays showed similar amounts of interferon-gamma transcripts in the two subsets; tumor necrosis factor-alpha, IL-4, and IL-10 transcripts were detected in CD4+CD7- T cells but not in their CD4+CD7+ counterparts. CONCLUSIONS: These data confirm the IL-2 production defect after bone marrow transplantation and suggest that the CD4+CD7- T-cell subset might be preferentially involved in the enhanced production of IL-4 and low production of IL-2. These data show that the early immune reconstitution in CD4+ T cells after SCT preferentially involves memory T cells with a Th0/Th2 differentiation that might participate in the T-helper cell defect.