The two major subsets of CD4+ helper T cells, designated Th1 and Th2, have quite different patterns of cytokine production and, as a consequence, have very different roles in immune responses. The articles in this volume review both basic and clinical studies of T cell heterogeneity, including: the mechanisms by which Th1 and Th2 cells develop and maintain their differences in cytokine production; the different roles of Th1 and Th2 cells in allergy, autoimmunity and infectious diseases; the prospects and strategies for therapeutic manipulation of Th1 and Th2 cells; and the control of Th1 and Th2 responses by regulatory T cell subsets. The volume should give the reader a view of the development and function of Th1 and Th2 cells and the attempts to treat immunological diseases with therapies directed towards altering the Th1/Th2 balance.
