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A comprehensive study of the cellular components of the immune system demands both deep and broad immunophenotyping of numerous cell subsets in an effective and practical way. Novel full-spectrum technology reveals the complete emission spectrum of each dye maximizing the amount of information that can be obtained on a single sample regarding conventional flow cytometry and provide an expanded knowledge of biological processes. In this chapter, we describe a 37-color protocol that allows to identify more than 45 different cell populations on whole blood samples of SARS-CoV-2-infected patients., (© 2022. The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature.)

Conventional analytical methods to determine telomere length (TL) have been replaced by more precise and reproducible procedures, such as fluorescence in situ hybridization coupled with flow cytometry (flow-FISH). However, simultaneous measurement of TL and cell phenotype remains difficult. Relatively expensive and time-consuming cell-sorting purification is needed to counteract the loss, due to stringent FISH conditions, of prehybridization fluorescence by the organic fluorochromes conventionally used in the phenotyping step. Here, we sought to assess whether the newly developed Brilliant Violet (BV) dyes are valuable to specifically and simultaneously assess the distribution and telomere attrition of monocyte subsets circulating in the blood of a cohort of patients with heart failure. We performed flow-FISH on blood samples from 28 patients with heart failure. To differentiate among monocyte subsets, we used BV and conventional fluorochromes conjugated to antibodies against CD86, CD14, CD16, and CD15. We simultaneously assessed the TLs of the monocyte subsets with a telomere-specific peptide nucleic acid probe labeled with fluorescein isothiocyanate. The BV dyes completely tolerated the harsh conditions required for adequate DNA denaturation and simultaneously provided accurate identification of monocyte subpopulations and respective TLs. The presented protocol may be faster and less expensive than those used currently for purposes such as establishing associations among patient categories, disease progression, monocyte heterogeneity, and aging in the context of heart failure.

Efforts to develop vaccines that can elicit mucosal immune responses in the female genital tract against sexually transmitted infections have been hampered by an inability to measure immune responses in these tissues. The differential expression of adhesion molecules is known to confer site-dependent homing of circulating effector T cells to mucosal tissues. Specific homing molecules have been defined that can be measured in blood as surrogate markers of local immunity (e.g. α4β7 for gut). Here we analyzed the expression pattern of adhesion molecules by circulating effector T cells following mucosal infection of the female genital tract in mice and during a symptomatic episode of vaginosis in women. While CCR2, CCR5, CXCR6 and CD11c were preferentially expressed in a mouse model of Chlamydia infection, only CCR5 and CD11c were clearly expressed by effector T cells during bacterial vaginosis in women. Other homing molecules previously suggested as required for homing to the genital mucosa such as α4β1 and α4β7 were also differentially expressed in these patients. However, CD11c expression, an integrin chain rarely analyzed in the context of T cell immunity, was the most consistently elevated in all activated effector CD8+ T cell subsets analyzed. This molecule was also induced after systemic infection in mice, suggesting that CD11c is not exclusive of genital tract infection. Still, its increase in response to genital tract disorders may represent a novel surrogate marker of mucosal immunity in women, and warrants further exploration for diagnostic and therapeutic purposes. [ABSTRACT FROM AUTHOR]

The characterization of host immune responses to human immunodeficiency virus (HIV) in HIV controllers and individuals with high exposure but seronegativity to HIV (HESN) is needed to guide the development of effective preventive and therapeutic vaccine candidates. However, several technical hurdles severely limit the definition of an effective virus-specific T-cell response. By using a toggle-peptide approach, which takes HIV sequence diversity into account, and a novel, boosted cytokine staining/flow cytometry strategy, we here describe new patterns of T-cell responses to HIV that would be missed by standard assays. Importantly, this approach also allows detection of broad and strong virus-specific T-cell responses in HESN individuals that are characterized by a T-helper type 1 cytokine–like effector profile and produce cytokines that have been associated with potential control of HIV infection, including interleukin 10, interleukin 13, and interleukin 22. These results establish a novel approach to improve the current understanding of HIV-specific T-cell immunity and identify cellular immune responses and individual cytokines as potential markers of relative HIV resistance. As such, the findings also help develop similar strategies for more-comprehensive assessments of host immune responses to other human infections and immune-mediated disorders. [ABSTRACT FROM AUTHOR]

Abstract: The host-cell reactivation assay (HCRA) is a functional assay that allows the identification of the genes responsible for DNA repair-deficient syndromes, such as Xeroderma pigmentosum, by cross-complementation experiments. It has also been used in molecular epidemiology studies to correlate the low nucleotide excision repair pathway function in peripheral blood lymphocytes with an increased risk of bladder, head and neck, skin and lung cancers. Herein, we present the technical validation of a newly modified HCRA, where nucleofection is used for the transfection of the pmaxGFP plasmid into cryopreserved peripheral blood lymphocytes (PBLs) or lymphoblastoid cell lines. In each sample, 20–24h after transfection, the relative DNA repair capacity (DRC) was quantified by flow cytometry, comparing the transfection efficiency of nucleoporated cells with undamaged plasmid to those transfected with UV-light damaged plasmid in the seven cell lines that were characterized by different DNA repair phenotypes. Dead cells were excluded from the analysis. We observed a high reproducibility of the relative DRC, transfection efficiency and cell viability. The inter-experimental normalization of the flow cytometry resulted in an increased data accuracy and reproducibility. The amount of cells required for each transfection reaction was reduced fourfold, without affecting the final relative DRC. Furthermore, our HCRA demonstrated strong discrimination power in the UV-light dose–response, both in lymphoblastoid cell lines and cryopreserved PBLs. We also observed a strong correlation of the relative DRC data, when samples were measured against two independent batches of both damaged and undamaged plasmid DNA. The relative DRC variable shows a normal distribution when analyzed in the cryopreserved PBLs from a cohort of 35 lung cancer patients and a 5.59-fold variation in the relative DRC is identified among our patients. The mitotic dynamic was discarded as a confounding factor for the relative DRC measurement in this cohort of patients. The results indicate that our method is highly sensitive, reliable and reproducible, and thus, it suitable for population-based studies to quantify in vitro DNA-repair deficiencies. [Copyright &y& Elsevier]