The second touch hypothesis: T cell activation, homing and polarization

Research output: Contribution to journalArticlepeer-review

31 Scopus citations


The second touch hypothesis states that T cell activation, proliferation, induction of homing receptors and polarization are distinguishable and, at least in part, sequential. The second touch hypothesis maintains that full T cell polarization requires T cell interaction with antigen-presenting cells (DCs, macrophages, B cells and certain activated stromal cells) in the non-lymphoid tissue where the antigen resides. Upon initial antigen encounter in peripheral lymph nodes (PLN), T cells become activated, proliferate and express homing receptors that enable them to recirculate to the (inflamed) tissue that contains the antigen. Differentiation into the T helper lineages Th1, Th2, Th17 and induced regulatory T cells (iTreg) requires additional antigen presentation by tissue macrophages and other antigen presenting cells (APCs) in the inflamed tissue. Here, I present a conceptual framework for the importance of peripheral (non-lymphoid) antigen presentation to antigen-experienced T cells.

Original languageEnglish (US)
Article number37.v1
StatePublished - Feb 5 2014
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Immunology and Microbiology(all)
  • Pharmacology, Toxicology and Pharmaceutics(all)


Dive into the research topics of 'The second touch hypothesis: T cell activation, homing and polarization'. Together they form a unique fingerprint.

Cite this