TH1 and TH2 cells: a historical perspective

Demonstration of the existence and functions of T helper (TH)1 and TH2 cells has had an enormous impact on basic and applied immunology. TH1 and TH2 cells have a crucial role in balancing the immune response. In this article, I attempt to trace the historical events contributing to the development of the TH1/TH2 concept, the current state of play, and briefly discuss the future prospects for the field.