Hierarchical cluster delineation results were validated using non-hierarchical cluster analysis (kappa inter-classification comparison agreement value κ=0.98). We conclude that this type of analysis can be used to objectively delineate T-cell clusters sharing identical features. We then attempted to determine,

using this approach, whether IL-22-secreting cells are more similar to the Th1 or Th17 subset. As shown in Fig. 2B, the branching point at which IFN-γ-secreting cells are parted from IL-17A- and/or IL-22-secreting cells is more distant from the extremity of the tree, as compared with the branching at which the latter are split into two subsets. As the magnitude of the distance for a given branch point separating two given clusters is directly correlated

with their degree of phenotypical buy Adriamycin differences, Th22 cells appear more closely related to Th17 than to Th1 cells, in PBMCs from the healthy individual taken as an example (Fig. 2B). To confirm this observation, cluster analysis was repeated using PBMCs from a series of healthy (n=12) and psoriasis (n=12) individuals. The results from this analysis confirmed that, in both groups, the distance of the branching point segregating the Th17 and Th22 subsets is significantly shorter than the distance segregating Th1 and any of the latter two subsets (Fig. 2D). Additional parameters (IL-2, TNF-α and CD161) were introduced in order to test their influence on the analysis. As shown in Fig. 2E, Crizotinib nmr the global clustering pattern was conserved when six parameters were used, except for Th1 cells, which were grouped Verteporfin ic50 into two distinct clusters

according to their capacity to secrete IL-2 or not. Altogether, six major clusters were defined using six parameters. This result further confirms the restricted number of dominant T-cell subsets sharing identical features, since here sixty-four (26) different clusters could theoretically have been delineated. According to this analysis, IFN-γ+IL-2+ cells would phenotypically be more related to IL-17A- and IL-22-secreting cells, than IFN-γ+IL-2− producers. Of note, the IL-17A and IL-22 parameters were found to cluster together and, importantly, away from IFN-γ. The same pattern was repeatedly observed in 20 out of 24 individuals analyzed (data not shown). Thus, Th17 and Th22 subsets are distinguishable and defined as separate entities, even when a more complex analysis is performed. As shown above, IL-17A- and IL-22-secreting cells are relatively scarce in periphery, even in psoriasis patients (Fig. 1 and Supporting Information Fig. S1). To determine whether these cells are more abundant in inflamed tissue lesions, infiltrating T cells were expanded in vitro from both healthy skin and psoriasis lesions of the same patients (n=3) and their cytokine production profiles analyzed by multiparametric flow cytometry (Supporting Information Fig. S3A).