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Eur J Immunol ; 51(12): 2708-3145, 2021 12.
Article in English | MEDLINE | ID: covidwho-1568038


The third edition of Flow Cytometry Guidelines provides the key aspects to consider when performing flow cytometry experiments and includes comprehensive sections describing phenotypes and functional assays of all major human and murine immune cell subsets. Notably, the Guidelines contain helpful tables highlighting phenotypes and key differences between human and murine cells. Another useful feature of this edition is the flow cytometry analysis of clinical samples with examples of flow cytometry applications in the context of autoimmune diseases, cancers as well as acute and chronic infectious diseases. Furthermore, there are sections detailing tips, tricks and pitfalls to avoid. All sections are written and peer-reviewed by leading flow cytometry experts and immunologists, making this edition an essential and state-of-the-art handbook for basic and clinical researchers.

Autoimmune Diseases/immunology , Flow Cytometry , Infections/immunology , Neoplasms/immunology , Animals , Chronic Disease , Humans , Mice , Practice Guidelines as Topic
PLoS Pathog ; 17(10): e1009742, 2021 10.
Article in English | MEDLINE | ID: covidwho-1456098


Disease manifestations in COVID-19 range from mild to severe illness associated with a dysregulated innate immune response. Alterations in function and regeneration of dendritic cells (DCs) and monocytes may contribute to immunopathology and influence adaptive immune responses in COVID-19 patients. We analyzed circulating DC and monocyte subsets in 65 hospitalized COVID-19 patients with mild/moderate or severe disease from acute illness to recovery and in healthy controls. Persisting reduction of all DC subpopulations was accompanied by an expansion of proliferating Lineage-HLADR+ cells lacking DC markers. Increased frequency of CD163+ CD14+ cells within the recently discovered DC3 subpopulation in patients with more severe disease was associated with systemic inflammation, activated T follicular helper cells, and antibody-secreting cells. Persistent downregulation of CD86 and upregulation of programmed death-ligand 1 (PD-L1) in conventional DCs (cDC2 and DC3) and classical monocytes associated with a reduced capacity to stimulate naïve CD4+ T cells correlated with disease severity. Long-lasting depletion and functional impairment of DCs and monocytes may have consequences for susceptibility to secondary infections and therapy of COVID-19 patients.

COVID-19/immunology , Dendritic Cells/immunology , Regeneration/immunology , SARS-CoV-2/immunology , Adult , Antigens, CD/immunology , CD4-Positive T-Lymphocytes/immunology , CD4-Positive T-Lymphocytes/pathology , COVID-19/pathology , Dendritic Cells/pathology , Female , Humans , Male , Middle Aged , Monocytes/immunology , Monocytes/pathology , Programmed Cell Death 1 Receptor/immunology
Eur J Immunol ; 51(6): 1325-1333, 2021 06.
Article in English | MEDLINE | ID: covidwho-1159066


T follicular helper (Tfh) cells play an essential role in regulating the GC reaction and, consequently, the generation of high-affinity antibodies and memory B cells. Therefore, Tfh cells are critical for potent humoral immune responses against various pathogens and their dysregulation has been linked to autoimmunity and cancer. Tfh cell differentiation is a multistep process, in which cognate interactions with different APC types, costimulatory and coinhibitory pathways, as well as cytokines are involved. However, it is still not fully understood how a subset of activated CD4+ T cells begins to express the Tfh cell-defining chemokine receptor CXCR5 during the early stage of the immune response, how some CXCR5+ pre-Tfh cells enter the B-cell follicles and mature further into GC Tfh cells, and how Tfh cells are maintained in the memory compartment. In this review, we discuss recent advances on how antigen and cognate interactions are important for Tfh cell differentiation and long-term persistence of Tfh cell memory, and how this is relevant to the current understanding of COVID-19 pathogenesis and the development of potent SARS-CoV-2 vaccines.

Antigens, Viral/immunology , COVID-19 Vaccines/immunology , COVID-19/immunology , Cell Differentiation/immunology , Immunologic Memory , SARS-CoV-2/immunology , T-Lymphocytes, Helper-Inducer/immunology , Animals , COVID-19/pathology , COVID-19/prevention & control , COVID-19 Vaccines/therapeutic use , Humans , T-Lymphocytes, Helper-Inducer/pathology