Viability of T lymphocytes survived in frozen-thawed human bone marrow

To know immunocompetence of cryopreserved human bone marrow, an optimal condition for cryopreservation of hemopoietic stem cells was determined on the basis of in vitro colony formation. Viability or immune function of frozen-thawed bone marrow lymphocytes was evaluated by spontaneous rosette formation and sheep red blood cells and mixed lymphocyte culture activity. It was demonstrated that the thawed marrow cells could form E rosettes and respond to alloantigens in mixed lymphocyte culture equally or more than those before freezing. Stimulating activity of cryopreserved marrow cells in mixed lymphocyte culture was not altered through a freeze-thawing process. These observations suggest that bone marrow lymphocytes may survive without losing their immunocompetence after freezing as well as hemopoietic stem cells.