Does IL-17 promote tumor growth?
Pawel Muranski, and Nicholas P. Restifo NATIONAL INSTITUTES OF HEALTH Chronic inflammatory conditions may augment tumor growth, but in this issue of Blood, Kryczek and colleagues1 find that endogenous IL-17 may not be one of the contributing factors. The association between chronic inflammatory conditions and the development of cancer was postulated by Rudolph Virchow in 1863. Indeed, many cancers arise at the sites of chronic irritation by chemical compounds or physical factors, infections, or autoimmune diseases through a plethora of mechanisms. Subsequent tumor progression is associated with invasion of surrounding tissues that causes further inflammatory changes, triggering recruitment of myeloid and lymphoid immune cells into the tumor microenvironment. Host cells can then release factors that contribute to either tumor progression or tumor inhibition.2 The precise regulation of the balance between cancer-promoting and antitumor factors involved in this process has yet to be under
