Ability of interleukin-4 to elicit an immunoreaction against a murine tumor.

A T cell-derived lymphokine, IL-4, has been shown to have activating and growth promoting properties on macrophages, T cells and B cells. IL-4 could thus be used to augment immunoreactivity in the treatment of tumors. To evaluate its ability to promote an immune reaction capable of hampering tumor growth, we injected mice with small amounts of recombinant IL-4 perilymphatically daily for ten days near the challenge site of a poorly immunogenic syngenic fibrosarcoma (CE-2). These low doses activated such a strong immune reaction that incipient syngenic tumors were rejected. Our results suggest that the host immune system plays a fundamental role in this IL-4 dependent lymphokine-activated tumor inhibition (LATI).