Enhancement by cyclophosphamide of experimental pulmonary metastases formation of Lewis lung carcinoma. II. Reduction of the cyclophosphamide effect by repopulation with cells from lymphoid organs.

Cyclophosphamide-induced enhancement of artificial lung metastasis of LL2 could be partly abolished by reconstituting of mice with spleen, lymph nodes or bone marrow cells but not with thymus cells. At cell dose of 10 x 10(6) per mouse the highest reconstituting capacity was found for spleen cells (73%) followed by bone marrow (60%) and lymph nodes cells (22%). Cell dose of 10(6) lymphoid cells per mouse did not reduce the CY-effect. The higher cell number (30 x 10(6) and 50 x 10(6) per mouse) did not abolish completely the CY-effect. The results indicate that in addition to sensitive lymphoid cells there exists another target for CY effect.