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Clonal expansion and development of immunological memory are two hallmarks of adaptive immune responses. Resolving the intricate pathways that regulate cell cycle activity and lead to the generation of diverse effector and memory T cell subsets is essential for improving our understanding of protective T cell immunity. A deeper knowledge of cell cycle regulation in T cells also has translational implications for adoptive cell therapies and vaccinations against infectious diseases. Here, we summarize recent evidence for an early diversification of effector and memory CD8+ T cell fates and discuss how this process is coupled to discrete changes in division speed. We further review technical advances in lineage tracing and cell cycle analysis and outline how these techniques have shed new light on the population dynamics of CD8+ T cell responses, thereby refining our current understanding of the developmental organization of the memory T cell pool. [ABSTRACT FROM AUTHOR]

T cell ignorance is a specific form of immunological tolerance. It describes the maintenance of naivety in antigen‐specific T cells in vivo despite the presence of their target antigen. It is thought to mainly play a role during the steady state, when self‐antigens are presented in absence of costimulatory signals and at low density or to T cells of low affinity. In how far antigen‐specific T cells can also remain clonally ignorant to foreign antigens, presented in the inflammatory context of systemic infection, remains unclear. Using single‐cell in vivo fate mapping and high throughput flow cytometric enrichment, we find that high‐affinity antigen‐specific CD8+ T cells are efficiently recruited upon systemic infection. In contrast, most low‐affinity antigen‐specific T cells ignore the priming antigen and persist in the naïve state while remaining fully responsive to subsequent immunization with a high‐affinity ligand. These data establish the widespread clonal ignorance of low‐affinity T cells as a major factor shaping the composition of antigen‐specific CD8+ T cell responses to systemic infection. [ABSTRACT FROM AUTHOR]

The two best presentations of the YI Symposium, chosen by the YI and NGI board, received the "Jochen Kalden Junior Prize", named after the former DGfI president and kindly sponsored by the Fritz and Ursula Melchers Foundation. Young Immunologists of the DGfI The Young Immunologists (YI) form a diverse network of ECRs within the DGfI. To celebrate immunology as a discipline and to promote collaborations among researchers in Europe, the German Society for Immunology (DGfI) organizes annual scientific meetings, where selected meetings are held together with another European immunological society. [Extracted from the article]

Memory differentiation of CD4 and CD8 T-cell populations has been extensively studied and many key molecular players and transcriptional networks have been identified. But how regulatory principles, identified on this population level, translate to immune responses that originate from single antigen-specific T cells is only now being elucidated. Here, we provide a short summary of the approaches used for mapping the fate of individual T cells and their progeny in vivo. We then highlight which major questions, with respect to memory T-cell differentiation, have been addressed by studying the development of single-cell-derived T-cell families during infection or vaccination. We discuss how fate decisions of single T cells are modulated by the affinity of their TCR and further shaped through a coregulation of T-cell differentiation and T-cell proliferation. These current findings indicate the early segregation into slowly dividing T central memory precursors (CMPs) and rapidly dividing non-CMPs, as a key event that separates the developmental paths of long- and short-lived T cells., (Copyright © 2021 Cold Spring Harbor Laboratory Press; all rights reserved.)

Subcorneal pustular dermatosis (SCPD, Sneddon-Wilkinson disease) is a rare chronic-relapsing skin disorder that typically manifests as flaccid sterile pustules without systemic symptoms. Although the accumulation of neutrophils is acknowledged to be a hallmark of SCPD, its exact pathomechanism is still not known. Several chemotactic factors have been implicated in neutrophil recruitment and invasion, including the proinflammatory cytokine TNF-α. These findings correspond well with clinical reports of successful off-label use of TNF blocking agents in cases that were refractory to first-line therapy, mostly with dapsone. We report the case of a 29-year-old male with atypical and severe manifestation of SCPD that resolved after a single dose of infliximab. Consolidation was observed 1 day after treatment and regression of skin lesions occurred after a few days. Residual scarring and postlesional hyperpigmentation was seen at a 2-month follow-up appointment. The patient was initiated on a daily maintenance therapy with dapsone, which led to a drop in hemoglobin and had to be stopped. Upon development of small, scaly lesions, a maintenance therapy with infliximab was started and the patient has had no recurrence to date. Anti-TNF agents present a promising option for patients affected by severe SCPD. We review the reports of similar cases in the literature to date.