Although we have not functionally evaluated the contribution of specific immune effector cell populations, we note that ablation of IL-11 responsiveness of the tumor stroma resulted in increased activity of CD4+ cells, thereby increasing cytotoxic responses against tumor cells in addition to the proposed CD4+ T cell–mediated aid to cytotoxic CD8+ cells responses (41, 42, 43). The gene discussed is IL11; the disease is neoplasm.