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Variability or stability might have an impact on treatment success and toxicity of CD19 CAR T-cells. We conducted a prospective observational study of 12 patients treated with Tisagenlecleucel for CD19 + B-cell malignancies. Using a 31-color spectral flow cytometry panel, we analyzed differentiation stages and exhaustion markers of CAR T-cell subsets prior to CAR T-cell infusion and longitudinally during 6 months of follow-up. The majority of activation markers on CAR T-cells showed stable expression patterns over time and were not associated with response to therapy or toxicity. Unsupervised cluster analysis revealed an immune signature of CAR T-cell products associated with the development of immune cell-associated neurotoxicity syndrome. Warranting validation in an independent patient cohort, in-depth phenotyping of CAR T-cell products as well as longitudinal monitoring post cell transfer might become a valuable tool to increase efficacy and safety of CAR T-cell therapy., Competing Interests: Author TS reports honoraria for lectures and travel grants from Alexion, Alnylam Pharmaceuticals, argenx, Bayer Vital, Biogen, Celgene, Centogene, CSL Behring, Euroimmun, Janssen, Merck Serono, Novartis, Pfizer, Roche, Sanofi, Siemens, Sobi, Teva, Viatris; all outside the submitted work. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The author(s) declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision., (Copyright © 2024 Odak, Bayir, Riemann, Sikora, Schneider, Xiao, Möhn, Skripuletz, Beutel, Eder, Ganser, Förster, Schultze-Florey and Koenecke.)

Identification of immune phenotypes linked to durable graft-versus-leukemia (GVL) response following donor lymphocyte infusions (DLI) is of high clinical relevance. In this prospective observational study of 13 AML relapse patients receiving therapeutic DLI, we longitudinally investigated changes in differentiation stages and exhaustion markers of T cell subsets using cluster analysis of 30-color spectral flow cytometry during 24 months follow-up. DLI cell products and patient samples after DLI were analyzed and correlated to the clinical outcome. Analysis of DLI cell products revealed heterogeneity in the proportions of naïve and antigen experienced T cells. Cell products containing lower levels of effector memory (eff/m) cells and higher amounts of naïve CD4 + and CD8 + T cells were associated with long-term remission. Furthermore, investigation of patient blood samples early after DLI showed that patients relapsing during the study period, had higher levels of CD4 + eff/m T cells and expressed a mosaic of surface molecules implying an exhausted functional state. Of note, this observation preceded the clinical diagnosis of relapse by five months. On the other hand, patients with continuous remission retained lower levels of exhausted CD4 + eff/m T cells more than four months post DLI. Moreover, lower frequencies of exhausted CD8 + eff/m T cells as well as higher amounts of CD4 + temra CD45RO + T cells were present in this group. These results imply the formation of functional long-term memory pool of T cells. Finally, unbiased sample analysis showed that DLI cell products with low levels of eff/m cells both in CD4 + and CD8 + T cell subpopulations associate with a lower relapse incidence. Additionally, competing risk analysis of patient samples taken early after DLI revealed that patients with high amounts of exhausted CD4 + eff/m T cells in their blood exhibited significantly higher rates of relapse. In conclusion, differentially activated T cell clusters, both in the DLI product and in patients post infusion, were associated with AML relapse after DLI. Our study suggests that differences in DLI cell product composition might influence GVL. In-depth monitoring of T cell dynamics post DLI might increase safety and efficacy of this immunotherapy, while further studies are needed to assess the functionality of T cells found in the DLI., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Odak, Sikora, Riemann, Bayir, Beck, Drenker, Xiao, Schneider, Dammann, Stadler, Eder, Ganser, Förster, Koenecke and Schultze-Florey.)

Evaluating long-term protection against SARS-CoV-2 variants of concern in convalescing individuals is of high clinical relevance. In this prospective study of a cohort of 46 SARS-CoV-2 patients infected with the Wuhan strain of SARS-CoV-2 we longitudinally analyzed changes in humoral and cellular immunity upon early and late convalescence. Antibody neutralization capacity was measured by surrogate virus neutralization test and cellular responses were investigated with 31-colour spectral flow cytometry. Spike-specific, isotype-switched B cells developed already during the disease phase, showed a memory phenotype and did not decrease in numbers even during late convalescence. Otherwise, no long-lasting perturbations of the immune compartment following COVID-19 clearance were observed. During convalescence anti-Spike (S1) IgG antibodies strongly decreased in all patients. We detected neutralizing antibodies against the Wuhan strain as well as the Alpha and Delta but not against the Beta, Gamma or Omicron variants for up to 7 months post COVID-19. Furthermore, correlation analysis revealed a strong association between sera anti-S1 IgG titers and their neutralization capacity against the Wuhan strain as well as Alpha and Delta. Overall, our data suggest that even 7 month after the clearance of COVID-19 many patients possess a protective layer of immunity, indicated by the persistence of Spike-specific memory B cells and by the presence of neutralizing antibodies against the Alpha and Delta variants. However, lack of neutralizing antibodies against the Beta, Gamma and Omicron variants even during the peak response is of major concern as this indicates viral evasion of the humoral immune response., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Odak, Schultze-Florey, Hammerschmidt, Ritter, Willenzon, Friedrichsen, Ravens, Sikora, Bayir, Gutierrez Jauregui, Bernhardt, Stankov, Cossmann, Hansen, Krey, Cornberg, Koenecke, Behrens, Bošnjak and Förster.)

Background: Control measures were instituted in a neonatal intensive care unit (NICU) in Syracuse, New York, when a neonatologist became ill with mumps after returning from Africa. Two health care providers (HCPs) who worked with the neonatologist developed parotitis within 13 days of exposure. Outbreak control included furloughing the neonatologist and the 2 HCPs until after 5 days of the onset of parotitis, cohorting and isolating all exposed infants in the NICU, and implementing droplet precautions. All susceptible HCPs were immunized, and all HCPs were required to wear surgical masks when within 3 feet of patients., Results: Five HCPs developed parotitis. The neonatologist and 2 of the HCPs were confirmed cases, and 2 other HCPs did not meet the case definition. Twenty-six HCPs who worked in other units of the hospital besides the NICU developed nonspecific signs and symptoms of illness. Of the 2,904 HCPs tested, 287 (10%) had negative antibody results, and 153 (8%) were age 40 years or older. Of the 287 HCPs with negative antibody titers, 200 (70%) received the mumps-measles-rubella vaccine in response to this effort. No cases of mumps were reported in exposed infants, children, or adult patients during the time of exposure., Conclusion: Infection control efforts, including vaccinating susceptible HCPs and instituting droplet precautions, might have prevented mumps infection in the NICU patients., (Copyright © 2011 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Mosby, Inc. All rights reserved.)