Distinctive expression of interleukin-23 receptor subunits on human Th17 and γδ T cells.

The interleukin-23 (IL-23) pathway, T helper 17 (Th17) cells and γδ T cells, which respond to IL-23, have major pro-inflammatory roles. We have used unique IL-23 receptor (IL-23R) subunit-specific monoclonal antibodies, X67 and X68, and IL-12 receptor beta-1 subunit (IL-12Rß1) expression levels to evaluate the IL-23R complex on CD4 αß TCR Th17 cells and on γδ T cells. Both IL-23R and IL-12Rß1 subunits constitute the functional IL-23R. Expression of the IL-23R subunit by cultured Th17 cells was heterogeneous. Th17 cells expressed consistent high levels of the IL-12Rß1 subunit, which appeared a better predictor of responsiveness to IL-23 than the expression of the IL-23R subunit. Moreover, sorting memory CD4 T cells by high IL-12Rß1 expression selectively enriched cells committed to IL-17 production from the blood. IL-23R expression was also observed on freshly isolated and cultured γδ T cells and the cultured γδ T cells were not responsive to IL-23.

ZSWIM1: a novel biomarker in T helper cell differentiation.

The effector memory CD4+ Th17 cells play critical roles in bacterial immunity and pathological inflammation in autoimmune conditions. ZSWIM1 is a gene encoding a protein of unknown function in leukocytes-but containing a zinc finger SWIM motif. In peripheral blood mononuclear cells, the expression of ZSWIM1 is highest in lymphocytes, and in particular shows greatest abundance in naive CD4+ T cells. Upon polarisation of naïve CD4+ T cells, ZSWIM1 expression is retained in Th17 cells but is selectively down regulated in Th1 cells. Similarly in in vitro expanded effector memory CD4+ T cells, ZSWIM1 was more abundant in Th17 cells compared to Th1 or Th17 polyfunctional (Th17pf) cells, which produce IL-17A and IFNγ. Although stimulation of cytokine production by PMA and ionomycin reduced ZSWIM1 expression, the relative differences in abundance between the cell types were maintained. The activation sensitive nature of ZSWIM1 expression suggests that it may play a novel role in the development or function of T helper cells.

Isolation, expansion and characterisation of alloreactive human Th17 and Th1 cells.

Interleukin 17 producing T helper cells (Th17) and IFNγ producing Th1 cells are distinct subsets of effector memory CD4(+) T cells that are crucial to host immunity and have been linked to the pathology of certain inflammatory autoimmune diseases. We have developed a method for the isolation and long term culture of human Th17 and Th1 cells. Using allogeneic stimulation we have cultured homogeneous populations of Th17 and Th1 cells to large cell numbers. These alloreactive cell lines were established from CD4(+)CD45RO(+) memory T cells expressing, or lacking, CCR6 and CCR4. The Th17 cells were derived only from cells expressing both CCR6 and CCR4 whereas the Th1 cells, secreting IFNγ, were derived from cells lacking CCR6 and CCR4. The CCR6(+) and CCR4(+) memory T cells also gave rise to a third population of polyfunctional cells expressing both IL-17 and IFNγ. All cell populations expressed the TCR αß and the Th17 cells characteristically expressed CCR6, CCR4 and CD161. The use of this protocol will ultimately allow for the comparative analysis of the Th17 and Th1 cells.