Th1 or Th2: how an appropriate T helper response can be made.
Two types of T helper (Th) cells have been defined on the basis of their cytokine secretion patterns. The decision of a naive T cell to differentiate into Th1 or Th2 is crucial, since to a first approximation it determines whether a cell-mediated or humoral immune response is triggered against a particular pathogen, which profoundly influences disease outcome. Here we show that the internal behaviour of the T helper system, which emerges from regulatory mechanisms 'built into' the T helper system, itself can usually select the appropriate T helper response. This phenomenon arises from an initial Th1 bias together with the induction of Th1-->Th2 switches when Th1 effectors do not lead to efficient antigen clearance. The occurrence of these shifts is based on the antigen dose dependence of T helper differentiation, which is a consequence of asymmetries in cross-suppression. Critical for this feature is the rate with which Th2 cells undergo antigen-induced cell death.
Bergmann
C
C
Physik-Department T35, Technical University Munich, D-85748 Garching, Germany. bergmann@physik.tu-muenchen.de
Van Hemmen
J L
JL
Segel
L A
LA
D000818:Animals; D016207:Cytokines / Q000096:biosynthesis / Q000276:immunology; D006801:Humans; D008213:Lymphocyte Activation / Q000276:immunology; D018448:Models, Immunological; D018417:Th1 Cells / Q000276:immunology* / Q000378:metabolism; D018418:Th2 Cells / Q000276:immunology* / Q000378:metabolism
D016207:Cytokines