The mechanisms governing infiltration of lymphocytes into tumors remain poorly characterized, in spite of the critical impact of these cells on patient prognosis and therapeutic responses. High endothelial venules (HEV) are blood vessels found in lymphoid tissues, specialized in lymphocyte recruitment, but their implications in human cancer are unknown. In this article, we report the presence of MECA 79+ blood vessels displaying all the phenotypic characteristics of HEVs in most of the 319 human primary solid tumors, including melanomas, breast, ovarian, colon, and lung carcinomas, analyzed. Tumor HEVs were specifically located within lymphocyte-rich areas, and their density within the tumor stroma was a strong predictor of infiltration by CD3+ and CD8+ T cells as well as B cells. Large-scale flow cytometric and quantitative reverse transcriptase-PCR analyses in freshly operated breast tumors revealed that high densities of tumor HEVs correlated with increased naive, central memory and activated effector memory T-cell infiltration and upregulation of genes related to T-helper 1 adaptive immunity and T-cell cytotoxicity. Finally, in a retrospective cohort of 146 invasive breast cancer patients, we found that high densities of tumor HEVs independently conferred a lower risk of relapse and significantly correlated with longer metastasis-free, disease-free, and overall survival rates. Together, our findings suggest that tumor HEVs function as major gateways for lymphocyte infiltration into human tumors, and may represent attractive targets for cancer diagnosis and therapy. Cancer Res; 71(17); 5678–87. ©2011 AACR.

In healthy adults, the major peripheral blood γδ T-cell subset expresses the Vγ9Vδ2 TCR and displays pleiotropic features. Here we report that coculture of naive Vγ9Vδ2 T cells with phosphoantigens and a cocktail of cytokines (IL-1-β, TGF-β, IL-6, and IL-23), leads to selective expression of the transcription factor RORγt and polarization toward IL-17 production. IL-17⁺ Vγ9Vδ2 T cells express the chemokine receptor CCR6 and produce IL-17 but neither IL-22 nor IFN-γ; they have a predominant terminally differentiated (CD27⁻CD45RA⁺) phenotype and express granzyme B, TRAIL, FasL, and CD161. On antigen activation, IL-17⁺ Vγ9Vδ2 T cells rapidly induce CXCL8-mediated migration and phagocytosis of neutrophils and IL-17–dependent production of β-defensin by epithelial cells, indicating that they may be involved in host immune responses against infectious microorganisms. Accordingly, an increased percentage of IL-17⁺ Vγ9Vδ2 lymphocytes is detected in the peripheral blood and at the site of disease in children with bacterial meningitis, and this pattern was reversed after successful antibacterial therapy. Most notably, the phenotype of IL-17⁺ Vγ9Vδ2 T cells in children with meningitis matches that of in vitro differentiated IL-17⁺ Vγ9Vδ2 T cells. Our findings delineate a previously unknown subset of human IL-17⁺ Vγ9Vδ2 T lymphocytes implicated in the pathophysiology of inflammatory responses during bacterial infections.

γδ T lymphocytes represent ∼1% of human peripheral blood mononuclear cells and even more cells in most tissues of vertebrates. Although they have important anticancer functions, most current single-cell RNA sequencing (scRNA-seq) studies do not identify γδ T lymphocytes because their transcriptomes at the single-cell level are unknown. Here we show that high-resolution clustering of large scRNA-seq datasets and a combination of gene signatures allow the specific detection of human γδ T lymphocytes and identification of their T cell receptor (TCR)Vδ1 and TCRVδ2 subsets in large datasets from complex cell mixtures. Int-distributed stochastic neighbor embedding plots from blood and tumor samples, the few γδ T lymphocytes appear collectively embedded between cytotoxic CD8 T and NK cells. Their TCRVδ1 and TCRVδ2 subsets form close yet distinct subclusters, respectively neighboring NK and CD8 T cells because of expression of shared and distinct cytotoxic maturation genes. Similar pseudotime maturation trajectories of TCRVδ1 and TCRVδ2 γδ T lymphocytes were discovered, unveiling in both subsets an unattended pool of terminally differentiated effector memory cells with preserved proliferative capacity, a finding confirmed by in vitro proliferation assays. Overall, the single-cell transcriptomes of thousands of individual γδ T lymphocytes from different CMV⁺and CMV⁻donors reflect cytotoxic maturation stages driven by the immunological history of donors. This landmark study establishes the rationale for identification, subtyping, and deep characterization of human γδ T lymphocytes in further scRNA-seq studies of complex tissues in physiological and disease conditions.

Contribution of Vγ9/Vδ2 T lymphocytes to immune protection against Mycobacterium tuberculosis is still a matter of debate. It was reported earlier th

T-cell antigen receptors composed of gamma and delta polypeptide chains (gammadelta TCRs) can directly recognize antigens in the form of intact proteins or non-peptide compounds, unlike alphabeta TCRs, which recognize antigens bound to major histocompatibility complex molecules (MHC). About 5% of peripheral blood T cells bear gammadelta TCRs, most of which recognize non-peptide phosphorylated antigens. Here we describe the 3.1 A resolution structure of a human gammadelta TCR from a T-cell clone that is phosphoantigen-reactive. The orientation of the variable (V) and constant (C) regions of the gammadelta TCR is unique when compared with alphabeta TCRs or antibodies, and results from an unusually small angle between the Vgamma and Cgamma domains. The complementarity-determining regions (CDRs) of the V domains exhibit a chemically reasonable binding site for phosphorylated antigens, providing a possible explanation for the canonical usage of the Vgamma9 and Vdelta2 gene segments by phosphoantigen-reactive receptors. Although the gammadelta TCR V domains are similar in overall structure to those of alphabeta TCRs, gammadelta TCR C domains are markedly different. Structural differences in Cgamma and Cdelta, and in the location of the disulphide bond between them, may enable gammadelta TCRs to form different recognition/signalling complexes than alphabeta TCRs.

Dendrimers are highly branched “tree-like” polymers that have demonstrated therapeutic potential in drug delivery, medical imaging, and tissue engineering in recent years. In addition, we have shown that an azabisphosphonate (ABP)–capped dendrimer selectively targets monocytes and directs them toward anti-inflammatory activation. We explored this property to assess the therapeutic potential of dendrimer ABP in the treatment of an inflammatory disease, rheumatoid arthritis. Intravenous injections of dendrimer ABP inhibited the development of inflammatory arthritis in two animal models: IL-1ra^−/− mice and mice undergoing K/BxN serum transfer. Suppression of disease was characterized by normal synovial membranes, reduced levels of inflammatory cytokines, and the absence of cartilage destruction and bone erosion. Dendrimer ABP also exhibited anti-osteoclastic activity on mouse and human cells, mediated by c-FMS (cellular-feline McDonough strain sarcoma virus oncogene homolog) inhibition. These preclinical demonstrations suggest the potential use of dendrimer ABP as a nanotherapeutic for rheumatoid arthritis.