Crohn’s-associated invariant T cells (CAITs) recognise small sulfonate molecules on CD1d

In the recent study by Rosati et al, we described a novel unconventional T cell population enriched in the peripheral blood of patients with Crohn’s disease (CD) and characterised by a semi-invariant T cell receptor (TCR) repertoire.1 However, the specificity of these Crohn’s-associated invariant T (CAIT) cells was not defined. Identifying the specificity of CAIT cells is essential to understand the origin of the antigen triggering their enrichment in CD. In our previous study, we observed that CAIT cells have TCRs similar to those reported for some natural killer T (NKT) type II cells.2 3 Here, we performed a sequence similarity analysis4 and identified a large cluster composed of CAIT clonotypes and three reported NKT type II clonotypes (figure 1A). While the NKT type II and CAIT clonotypes all had highly similar TCR alpha chains carrying TRAV12-1/TRAJ6 genomic segments, their beta chains were highly diverse (figure 1A, bottom). Dash et al have shown that TCRs with similar sequences frequently have the same specificity.5 6 In the original publications describing these clonotypes, the authors reported that the NKT type II cells recognise small molecules of the pentamethylbenzofuransulfonates (PBFs) family presented by the invariant HLA-like CD1d protein.2 3 Thus, we investigated whether CAIT TCRs shared the specificity of the NKT type II cells. Figure 1 Comparison of natural killer T (NKT) type II and Crohn’s-associated invariant T (CAIT) cells. (A) Sequence similarity analysis of NKT type II2 …