The effectiveness of intravenously administered immune lymphoid cells against intraperitoneally growing tumor correlates with their homing in the recipients' lymphoid organs.

ABSTRACT

Intraperitoneally growing Ehrlich ascites tumor (EAT) was eradicated by both i.p. and i.v. injection of serum, and by i.p. injection of spleen cells from mice immune to EAT. However, the i.v. injected immune spleen cells were completely ineffective unless the recipients had been pretreated with cyclophosphamide. The analysis of immune response in mice cured by the combination of cyclophosphamide and cell transfer revealed that they developed a humoral-type immunity to EAT and that the transferred spleen cells did not penetrate into their abdominal cavity. The effect of cyclophosphamide correlated with the extent of seeding of the donor-type cells in the recipients' lymphoid organs. Inasmuch as homing in cyclophosphamide-pretreated mice surpassed that in normal mice three to four times, it appeared that the beneficial effect of cyclophosphamide was primarily founded on its enhancement of seeding of the transferred lymphoid cells, implying that homing of these cells is a prerequisite for their anti-tumor activity.