Development of immunocompetent lymphocytes in vivo from murine umbilical cord blood cells.

ABSTRACT

BACKGROUND: Reports concerning the immunological functions of lymphocytes derived from umbilical cord blood cell (UCBC) have been limited. METHODS: In murine syngeneic transplantation system using green fluorescent protein transgenic donors, UCBC-derived lymphocytes were studied for their immunological competence. RESULTS: Hematopoietic stem cells (HSC) among UCBC differentiated in the recipients into phenotypically mature T and B lymphocytes. The T lymphocytes were capable of specific recognition of major histocompatibility complex/peptide complex and of the subsequent activation. The antigen-induced CD4(+) T cells produced lymphokine upon in vitro antigen stimulation. CD8(+) T cells simulated in the mixed lymphocyte culture could lyze specific target cells. Furthermore, RAG2(-/-) mice reconstituted with UCBC mounted specific antibody responses to T-dependent antigen comparable to those by bone marrow chimeras and also rejected allogeneic skin grafts. CONCLUSION: Collectively the data indicated that T and B lymphocytes derived from UCBC-HSC are fully competent in immunological terms.