Blastogenic response of activated human umbilical cord blood T-lymphocytes.

Donor T-lymphocytes are thought to play a crucial role in both acute and chronic graft-versus-host disease (GvHD), pathological conditions that frequently complicate allogeneic bone marrow transplantation. These diseases are described as occurring with a lower incidence and lesser severity when human umbilical cord blood (HUCB) cells, which have recently emerged as a potential source of hematopoietic progenitors, are used for transplantation. This condition is probably related to the immaturity of neonatal HUCB T cells. Lymphocyte blastogenic response to phytohemagglutinin (PHA), evaluated by means of flow cytometry, is a useful tool for testing the functional ability of T-cells to display an immune response against allo-antigens, reproducing in vitro the in vivo mechanism of activation. This study was designed to verify whether an impairment in HUCB T-cell ability to undergo an in vitro blastogenic response to mitogens could explain their reduced in vivo ability to induce GvHD.