The Secrets of T Cell Polarization

Abstract

The aim of chemotherapy and radiotherapy is to eliminate tumor cells. While the outcomes of these cytotoxic treatments were previously attributed to their direct effects on tumor cells, it is now clear that the host’s immune system, and specifically T cells, also contributes to the success of these therapies. These observations, along with the demonstrated clinical successes of anticancer agents targeting T cells have prompted scientists to revisit the mechanisms responsible for T cell polarization. In 1986, Mossman and Coffman have reported the ability of naive CD4 T cells to differentiate into specialized variants, designed as Th1 and Th2 and differing in their profiles of lymphokine activities. Since then, it was shown that both CD4 and CD8 T cells could differentiate in a myriad of effector T cell subsets that have a profound impact on adaptive immunity. In this chapter, we review the molecular mechanisms responsible for the differentiation of T cells and their relevance for human disease.