Differential production of interferon-γ and interleukin-4 in response to Th1- and Th2-stimulating pathogens by γδ T cells in vivo

Abstract

EXPOSURE to various pathogens can stimulate at least two patterns of cytokine production by CD4-positive T cells^1–4. Responses that result in secretion of interferon-γ (IFN-γ), lymphotoxin and interleukin-2 (IL-2) are classified as T-helper-1 (Th1)^5,6; CD4⁺ T-cell production of IL-4, IL-5, IL-9, IL-10 and IL-13 is called a T-helper-2 response (Th2)^5,6. Differentiation of CD4⁺ T cells into either Th1 or Th2 cells is influenced by the cytokine milieu in which the initial antigen priming occurs^7–9. Here we use flow cytometry to identify the presence of intracellular cytokines (cytoflow) and analyse T-cell production of IFN-γ and IL-4 from mice infected with Listeria monocytogenes or Nippostrongylus brasiliensis. We show that T cells bearing γδ receptors discriminate early in infection between these two pathogens by producing cytokines associated with the appropriate T-helper response. Our results demonstrate that γδ T cells are involved in establishing primary immune responses.