Abstract
The development of T helper 1 versus T helper 2 cells is a major branch point in the immune response and is an important determinant of the body's response to an infectious pathogen, leading to protection of the host or dissemination of the disease. Recent studies have shown that there exist macrophage activation states in parallel to the T helper cell type 1/2 paradigm, and the T helper 1 development process is governed to a great degree by cytokine IL-12 provided mainly by antigen presenting cells such as macrophages and dendritic cells. A model in patients with hepatitis is proposed that links the pathogen, macrophage activation and T helper cell polarization.