Medium conditioned by pokeweed-mitogen-activated human spleen cells enhances the survival of human multipotent stem cells (CFU-mix), erythroid progenitors (BFU-E), and myeloid progenitors (CFU-C) in liquid culture. The effect of adenosine on bone marrow cell survival in liquid culture in the presence of 2′deoxycoformycin and pokeweed-mitogen spleen-conditioned medium was studied. The combination of 2′deoxycoformycin and adenosine was found to have opposite effects on T lymphocytes and hemopoietic progenitors, i.e., the latter were preserved whereas the growth of T lymphocytes was inhibited following prolonged (4-7 days) incubation in suspension culture. The combination of 2′deoxycoformycin and adenosine removed not only all antigenically detectable T cells, but also functionally detectable cells, as judged by response to mitogens. The results suggest that in vitro culture of bone marrow cells in the presence of 2′deoxycoformycin and adenosine might be considered as an alternative way for the removal of T lymphocytes for allogeneic bone marrow transplantation.