Growth of human colorectal tumor xenografts in immunosuppressed mice reconstituted with normal cells.

The growth of human colorectal tumor xenograft lines was studied in immunosuppressed mice after reconstitution with sensitized and nonsensitized macrophages, thymocytes and splenocytes obtained from normal mice. Intravenously injected macrophages caused temporary inhibition of tumor growth. This effect needed intact cells and was independent from the presence of the spleen. The weight of spleen increased in normal mice sensitized with xenograft tumor, and the sensitized splenocytes injected into tumor-bearing immunosuppressed mice caused substantial tumor-growth delay.