Histamine upregulates Th1 and downregulates Th2 responses due to differentpatterns of surface histamine 1 and 2 receptor expression

Histamine, which acts via G protein-coupled receptors, is an important medi ator of immediate hypersensitivity and is also able to influence the nature of T cell responses. We demonstrated that TH1 and Th2 cells express distin ct surface histamine receptor patterns and that Th1-type responses are enha nced by histamine, whereas Th2-type responses are negatively regulated, due to different intracellular signals generated by histamine stimulation. The se findings account for negative feedback regulation in a wide variety of p athologies. Copyright (C) 2001 S. Karger AG, Basel.