Human Th1 and Th2 lymphocytes: their role in the pathophysiology of atopy

Allergy. 1992 Oct;47(5):450-5. doi: 10.1111/j.1398-9995.1992.tb00662.x.


In human beings, as in mice, two distinct patterns of cytokine secretion have been defined among CD4+ helper T-cell clones. Human type 1 helper (Th1), but not type 2 helper (Th2), cells produce interleukin-2 (IL-2), gamma-interferon (IFN-gamma), and tumor necrosis factor-beta, whereas Th2, but not Th1, cells secrete IL-4 and IL-5, but not IL-2 or IFN-gamma. Other cytokines, such as IL-3, IL-6, GM-CSF, or TNF-alpha, are produced by both Th1 and Th2 cells. Th0 cells, a third Th subset, show combined production of Th1- and Th2-type cytokines. The different cytokine patterns are associated with different functions. In general, Th2 cells provide an excellent helper function for B-cell antibody production, particularly of the IgE class. On the other hand, Th1 cells are responsible for delayed type hypersensitivity reactions and are cytolytic for autologous antigen-presenting cells, including B cells. Most allergen- or helminth-antigen-specific human CD4+ T-cell clones exhibit a Th2 phenotype, whereas most clones specific for bacterial antigens show a Th1 profile. Allergen-specific Th2 cells seem to play a crucial role in atopy. These cells induce IgE production via IL-4 and favor the proliferation, differentiation, and activation of eosinophils via IL-5. In addition, Th2-derived IL-3 and IL-4 are mast-cell growth factors that act in synergy, at least in vitro. Recent evidence indicates that allergen-specific Th2 cells are selectively enriched in tissues affected by allergic inflammation, such as the bronchial mucosa of subjects with allergic asthma.(ABSTRACT TRUNCATED AT 250 WORDS)

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Allergens / immunology
  • Cytokines / biosynthesis
  • Cytokines / immunology
  • Humans
  • Hypersensitivity, Immediate / immunology
  • Hypersensitivity, Immediate / physiopathology*
  • Immunoglobulin E / biosynthesis
  • Immunoglobulin E / immunology
  • Interferon-gamma / biosynthesis
  • Interferon-gamma / immunology
  • Interleukin-4 / immunology
  • Mast Cells / immunology
  • Phenotype
  • T-Lymphocyte Subsets / immunology
  • T-Lymphocytes, Helper-Inducer / immunology*


  • Allergens
  • Cytokines
  • Interleukin-4
  • Immunoglobulin E
  • Interferon-gamma