The in vivo distribution of transferred syngeneic, allogeneic, and xenogeneic lymphoid cells: Implication for the adoptive immunotherapy of tumors

The differential distribution patterns of syngeneic, allogeneic, and xenogeneic lymphoid cells injected i.v. into C57BL/6 mice have been compared. Sixty to seventy per cent of the counts incorporated into live cells were retained by 48 hr whereas only 30 to 40% of counts in dead cells were retained by this time. Although there was no detectable difference in whole body retention of viable or dead cells when comparing syngeneic, allogeneic, and xenogeneic cells, the individual organ distributions differed significantly. Viable syngeneic and allogeneic cells distributed predominantly to the liver, spleen, and carcass of the animal whereas xenogeneic cells distributed predominantly to the liver of the animal with almost no counts found in the spleen. This rapid entrapment of xenogeneic cells in the liver of mice was not affected by treatment with irradiation or cyclophosphamide but was significantly reduced by treatment with reticuloendothelial system blockers such as methylpalmitate or carrageenan. These agents significantly increased distribution to the spleen and decreased distribution to the liver with the net result that distribution of xenogeneic lymphoid cells became more similar to that of syngeneic and allogeneic cells. These results suggest that one possible reason for the reported ineffectiveness of xenogeneic sensitized cells in adoptive immunotherapy may be the rapid entrapment of these cells by the liver and that RES blockers may prevent such entrapment.