Background: At border sites, and in internal organs, tissue resident memory T cells (T-RM) contribute to the immune barrier against pathogens like viruses, bacteria, fungi, and cancer. However,... Show moreBackground: At border sites, and in internal organs, tissue resident memory T cells (T-RM) contribute to the immune barrier against pathogens like viruses, bacteria, fungi, and cancer. However, information on the presence and function of these cells in the human kidney is scant. In order to better understand the T cell-mediated immunological defense in this organ, we aimed to determine phenotypic and functional aspects of CD8 and CD4 T cells present in healthy and allograft kidney tissue. Methods: Using multichannel flow cytometry, we assessed the phenotype and function of T cells in healthy renal tissue samples (n = 5) and kidney allograft tissue (n = 7) and compared these aspects to T cells in peripheral blood from healthy controls (n = 13). Results: Kidney tissue samples contained substantial amounts of CD8 and CD4 T cells. In contrast to the circulating cells, kidney T cells frequently expressed CD69 and CD103, and were more often actively cycling. Furthermore, nearly all kidney T cells expressed CXCR3, and often expressed CXCR6 compared to T cells in the circulation. Markedly, kidney T cells produced greater quantities of IFN gamma than circulating cells and were frequently polyfunctional. Conclusion: Functional T cells with the characteristic traits of T-RM reside in human kidney tissues. These cells are more often actively cycling and frequently express CXCR3 and CXCR6. Show less
Fernandes, R.A.; Perez-Andres, M.; Blanco, E.; Jara-Acevedo, M.; Criado, I.; Almeida, J.; ... ; EuroFlow Consortium 2019
Idiopathic T-CD4 lymphocytopenia (ICL) is a rare and heterogeneous syndrome characterized by opportunistic infections due to reduced CD4 T-lymphocytes (<300 cells/mu l or <20% T-cells) in the... Show moreIdiopathic T-CD4 lymphocytopenia (ICL) is a rare and heterogeneous syndrome characterized by opportunistic infections due to reduced CD4 T-lymphocytes (<300 cells/mu l or <20% T-cells) in the absence of HIV infection and other primary causes of lymphopenia. Molecular testing of ICL has revealed defects in genes not specific to CD4 T-cells, with pleiotropic effects on other cell types. Here we report for the first time an absolute CD4 lymphocytopenia (<0.01 CD4(+) T-cells/mu l) due to an autosomal recessive CD4 gene mutation that completely abrogates CD4 protein expression on the surface membrane of T-cells, monocytes, and dendritic cells. A 45-year-old female born to consanguineous parents consulted because of exuberant, relapsing, and treatment-refractory warts on her hands and feet since the age of 10 years, in the absence of other recurrent infections or symptoms. Serological studies were negative for severe infections, including HIV 1/2, HTLV-1, and syphilis, but positive for CMV and EBV. Blood analysis showed the absence of CD4(+) T-cells (<0.01%) with repeatedly increased counts of B-cells, naive CD8(+) T-lymphocytes, and particularly, CD4/CD8 double-negative (DN) TCR alpha beta(+) TCR gamma delta(-) T-cells (30% of T-cells; 400 cells/mu l). Flow cytometric staining of CD4 using monoclonal antibodies directed against five different epitopes, located in two different domains of the protein, confirmed no cell surface membrane or intracytoplasmic expression of CD4 on T-cells, monocytes, and dendritic cells but normal soluble CD4 plasma levels. DN T-cells showed a phenotypic and functional profile similar to normal CD4(+) T-cells as regards expression of maturation markers, T-helper and T-regulatory chemokine receptors, TCRv beta repertoire, and in vitro cytokine production against polyclonal and antigen-specific stimuli. Sequencing of the CD4 gene revealed a homozygous (splicing) mutation affecting the last bp on intron 7-8, leading to deletion of the juxtamembrane and intracellular domains of the protein and complete abrogation of CD4 expression on the cell membrane. These findings support previous studies in CD4 KO mice suggesting that surrogate DN helper and regulatory T-cells capable of supporting antigen-specific immune responses are produced in the absence of CD4 signaling and point out the need for better understanding the role of CD4 on thymic selection and the immune response. Show less
