Cord blood serum does not increase lymphocyte responses in comparison to adult serum

To date, over 1000 cord blood (CB) transplants have been reported from different centers worldwide and it is generally agreed that CB represents an encouraging alternative to bone marrow (BM) transplantation. There are a variety of reasons for this, however, possibly the two most controversial aspects are (a) whether there is less graft versus host disease (GVHD) with CB compared to BM transplantation, and (b) whether we can use more HLA mismatches with CB transplantation. The major theory regarding the reduced immunological response of CB lymphocytes is that CB T and NK cells are naive and, therefore, not primed for activation. However, the naive phenomena that has been noted in vitro may be bypassed in vivo by unforeseen factors. We show evidence that there are differences in the soluble factors present in CB and adult serum and that these differences play a role in T cell function. Thus, adult serum will enhance both mitogen and IL-2 specific T cell growth whereas CB serum has no effect, suggesting that there is an activation/growth factor present in adult sera, which is absent in CB sera. This work could enable us to identify the molecular mechanisms which are associated with a lower GVHD in CB compared to BM transplanted individuals.