Harnessing the immune system to treat cancer

Abstract

A major challenge for the immune system is to recognize and eliminate cells undergoing carcinogenesis. Immune defense against tumors is complex. It can be mediated early by the innate immune system (i.e., phagocytes, NK cells, NKT cells, cytokines, and complement proteins) and later by the adaptive immune system (i.e., B cells and T cells). The eight articles in this Review series on tumor immunology discuss the mechanisms underlying immune surveillance of tumors, the regulation of carcinogenesis by immune inflammatory mediators, current approaches to controlling tumor growth through immunotherapy, and novel targets of immunotherapy.

Figure 1. Some of the immunological factors discussed in this Review series that affect tumor development.

Cells of both the innate and adaptive arms of the immune system can mediate antitumor immunity, including CTLs, CD4⁺ T cells, B cells, and NK cells. However, as tumors progress, they often develop ways in which to escape immune recognition. For example, they can induce the production of proinflammatory cytokines, the expression of IDO by APCs, and the differentiation of Tregs and various suppressor cells of myeloid origin. TAM, tumor-associated macrophage.