Early studies of human CD1-restricted T cells focused on double-negative T cells (DN T cells), which lack CD4 and CD8 co-receptors. These DN T cells were thought to preferentially interact with antigen presenting molecules other than MHC, such as CD1, since interactions with MHC class I and II require the CD8 and CD4 co-receptor, respectively. Indeed, TCR sequencing of the DN T cell repertoire led to the identification of invariant TCRα chains that were later linked to CD1d-restricted invariant NKT cells and to MR1-restricted MAIT cells. Overall, DN αβ T cells are a small population of T cells in peripheral blood, constituting approximately 1% of all T cells. However, their frequency is higher in certain tissues, such as kidney and intestine, and importantly, DN T cells expand significantly in certain autoimmune conditions, in particular Systemic Lupus Erythematosus (SLE). This supports the notion that DN T cells are clinically important T cells that play a role in autoimmune conditions. We have revisited the human double-negative T cell repertoire, asking the following questions: Are CD1-restricted T cells indeed enriched in the DN T cell fraction compared to the CD4 and CD8 T cell fractions? Can we identify conserved CD1-restricted T cell subsets beyond iNKT cells and MAIT cells among DN T cells, by linking TCR sequencing data to gene expression data? Using fluorescently-labeled CD1a, CD1b, CD1c, and CD1d tetramers for ex vivo quantification, as well as in vitro CD1-dependent T cell stimulation assays, we determined that the frequencies of CD1 tetramer+ T cells for all CD1 isoforms were significantly higher in the DN T cell fraction than in either CD4 or CD8 T cell fractions, suggesting that CD1-restricted T cells are indeed enriched among DN T cells. In line with this, CD1-autoreactive T cell lines were readily generated from DN T cells, even without CD1 tetramer-based enrichment. Single cell RNA-sequencing and TCR-sequencing of DN T cells isolated from 15 healthy donors, confirmed the presence of known T cell populations (iNKT cells, MAIT cells) in DN T cells of all donors tested. It also revealed the presence of preferential TRAV-TRAJ usage and CDR3 motifs shared between donors, although these were less conserved than the known invariant TCRα chains. We are now using Clonotype Neighbor Graph Analysis (CoNGA) to identify correlations between gene expression profile and TCR sequence through statistical analysis of gene expression and TCR similarity graphs, and further linking TCR sequences to CD1-specificities. These studies will provide a detailed and comprehensive view of CD1-restricted T cell populations within the human DN T cell repertoire, and provide a resource for further investigating these populations in disease.