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BACKGROUND: During allogeneic Hematopoietic stem cell transplantation (HSCT), frequent pathological scenarios include graft versus host disease (GVHD) and viral infections. We hypothesized if exogenous stimulus as alloantigen and viral antigens might impact on central and effector memory T cells in pediatric recipients. PATIENTS AND METHODS: Subjects included 21 pediatric recipients and 20 healthy children (control group). Peripheral blood samples of patients were collected along the first 712 days post-HSCT. T cell phenotyping of naïve, central, and effector memory T cells (TCMs and TEMs, respectively) was conducted using flow cytometry. Viral nucleic acids were detected using real-time PCR. RESULTS: T cell reconstitution was not reached after 1 year post-HSCT. Chronic GVHD was associated with increased numbers of naïve CD4 T cells (p < 0.05) as well as an increase in TEM and TCM cells of the CD4 (p < 0.0001 and p < 0.05, respectively) and CD8 T cell TEM (p < 0.0001). and TCM (p < 0.001) populations too. Moreover, BK and Epstein-Barr viruses were the main viral pathogens detected (<104 copies), which were associated with a decrease in all T cell compartments. CONCLUSION: During chronic GVHD, alloantigen persistence generates TEM cell enrichment among CD4 and CD8 T cells, and viral infections are associated with deficient recovery of T cells after HSCT.

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Abstract Objective: The prognostic importance of Tumor-Infiltrating Lymphocytes (TILs) in the tumor microenvironment of various cancers is increasingly recognized. In the present study, we aimed to investigate the prognostic value of CD3+, CD4+, CD8+, and CD45RO + TILs and their relation to histopathological features in larynx squamous cell carcinoma. Methods: Formalin-Fixed and Paraffin-Embedded (FFPE) samples from 63 primary larynx squamous cell carcinoma patients were immunostained for CD3, CD4, CD8, and CD45RO expression. Positive cells in micrographs from Invasive Margin (IM) and Tumor Center (CT) of tissue specimens counted by ImageJ software and their correlation with disease outcome were analyzed. Results: The expression level of TILs subpopulations was associated with clinicopathological markers as well as Overall Survival (OS) and Disease-Free Survival (DFS). In multivariate analysis, high frequency of CD45RO + cells in IM were confirmed as an independent prognostic marker for DFS (p = 0.007, HR = 4.968) and OS (p = 0.007, HR = 4.957). Similar findings were observed in the multivariate analysis of the combined frequency of CD45RO+cells in IM and CT. Conclusion: TILs are associated with patients clinicopathological features. Also, our findings indicate that CD45RO + TILs are a valuable marker for risk prediction in larynx SCC and could predict patients' outcomes.

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OBJECTIVE: The prognostic importance of Tumor-Infiltrating Lymphocytes (TILs) in the tumor microenvironment of various cancers is increasingly recognized. In the present study, we aimed to investigate the prognostic value of CD3+, CD4+, CD8+, and CD45RO + TILs and their relation to histopathological features in larynx squamous cell carcinoma. METHODS: Formalin-Fixed and Paraffin-Embedded (FFPE) samples from 63 primary larynx squamous cell carcinoma patients were immunostained for CD3, CD4, CD8, and CD45RO expression. Positive cells in micrographs from Invasive Margin (IM) and Tumor Center (CT) of tissue specimens counted by ImageJ software and their correlation with disease outcome were analyzed. RESULTS: The expression level of TILs subpopulations was associated with clinicopathological markers as well as Overall Survival (OS) and Disease-Free Survival (DFS). In multivariate analysis, high frequency of CD45RO + cells in IM were confirmed as an independent prognostic marker for DFS (p = 0.007, HR = 4.968) and OS (p = 0.007, HR = 4.957). Similar findings were observed in the multivariate analysis of the combined frequency of CD45RO+cells in IM and CT. CONCLUSION: TILs are associated with patients clinicopathological features. Also, our findings indicate that CD45RO + TILs are a valuable marker for risk prediction in larynx SCC and could predict patients' outcomes.

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Convalescent plasma (CP) has emerged as a treatment for COVID-19. However, the composition and mechanism of action are not fully known. Therefore, we undertook a two-phase controlled study in which, first the immunological and metabolomic status of recovered and severe patients were evaluated. Secondly, the 28-day effect of CP on the immune response in severe patients was assessed. Nineteen recovered COVID-19 patients, 18 hospitalized patients with severe disease, and 16 pre-pandemic controls were included. Patients with severe disease were treated with CP transfusion and standard therapy (i.e., plasma recipients, n = 9) or standard therapy alone (n = 9). Clinical and biological assessments were done on day 0 and during follow-up on days 4, 7, 14, and 28. Clinical parameters, viral load, total immunoglobulin (Ig) G and IgA anti-S1-SARS-CoV-2 antibodies, neutralizing antibodies (NAbs), autoantibodies, cytokines, T and B cells, and metabolomic and lipidomic profiles were examined. Total IgG and IgA anti-S1-SARS-CoV-2 antibodies were key factors for CP selection and correlated with NAbs. In severe COVID-19 patients, mostly interleukin (IL)-6 (P = <0.0001), IL-10 (P = <0.0001), IP-10 (P = <0.0001), fatty acyls and glycerophospholipids were higher than in recovered patients. Latent autoimmunity and anti-IFN-α antibodies were observed in both recovered and severe patients. COVID-19 CP induced an early but transient cytokine profile modification and increases IgG anti-S1-SARS-CoV-2 antibodies. At day 28 post-transfusion, a decrease in activated, effector and effector memory CD4+ (P < 0.05) and activated and effector CD8+ (P < 0.01) T cells and naïve B cells (P = 0.001), and an increase in non-classical memory B cells (P=<0.0001) and central memory CD4+ T cells (P = 0.0252) were observed. Moreover, IL-6/IFN-γ (P = 0.0089) and IL-6/IL-10 (P = 0.0180) ratios decreased in plasma recipients compared to those who received standard therapy alone. These results may have therapeutic implications and justify further post-COVID-19 studies.

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CD8 T cells play a crucial role in immune responses to virus infections and tumors. Naïve CD8 T lymphocytes after TCR stimulation undergo differentiation into CTLs and memory cells, which are essential sources of IFN-γ. We investigated IFN-γ production by CD8 T cell subsets found in nonimmune mice. A minor fraction of in vitro TCR-stimulated CD8 T cells produce IFN-γ, and it is regulated at the transcriptional level. Antigen inexperienced C57BL/6 mice present the coexistence of 2 populations. The main population exhibits a CD44low CD122low profile, which is compatible with naïve lymphocytes. The minor expresses a phenotype of immunologic memory, CD44hi CD122hi . Both subsets are able to produce IL-2 in response to TCR activation, but only the memory-like population is responsible for IFN-γ production. Similar to memory CD8 T cells, CD44hi CD8+ T cells also present a higher level of the transcriptional factor Eomes and a lower level of T-bet (Tbx21) mRNA than CD44low CD8+ T cells. The presence of the CD44hi CD8+ T cell population in nonimmune OT-I transgenic mice reveals that the population is generated independently of antigenic stimulation. CpG methylation is an efficient epigenetic mechanism for gene silencing. DNA methylation at posttranscriptional CpG sites in the Ifng promoter is higher in CD44low CD8+ T cells than in CD44hi CD8+ T cells. Thus, memory-like CD8 T cells have a distinct epigenetic pattern in the Ifng promoter and can rapidly produce IFN-γ in response to TCR stimulation.

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The cells T CD4+ T and CD8+ can be subdivided into phenotypes naïve, T of central memory, T of effector memory and effector, according to the expression of surface molecules CD45RO and CD27. The T lymphocytes are cells of long life with capacity of rapid expansion and function, after a new antigenic exposure. In tuberculosis, it was found that specific memory T cells are present, however, gaps remain about the role of such cells in the disease immunology. In this study, the phenotypic profile was analyzed and characterized the functionality of CD4+ T lymphocytes and CD8+ T cells of memory and effector, in response to specific stimuli in vitro, in patients with active pulmonary TB, compared to individuals with latent infection with Mycobacterium tuberculosis the ones treated with pulmonary TB. It was observed that the group of patients with active pulmonary tuberculosis was the one which presented the highest proportion of cells T CD4+ of central memory IFN-É£+ e TNF-α+, suggesting that in TB, these T of central memory cells would have a profile of protective response, being an important target of study for the development of more effective vaccines; this group also developed lower proportion of CD8+ T effector lymphocytes than the others, a probable cause of specific and less effective response against the bacillus in these individuals; the ones treated for pulmonary tuberculosis were those who developed higher proportion of T CD4+ of memory central IL-17+ cells, indicating that the stimulation of long duration, with high antigenic load, followed by elimination of the pathogen, contribute to more significant generation of such cells; individuals with latent infection by M. tuberculosis and treated for pulmonary tuberculosis, showed greater response of CD8+ T effector lymphocytes IFN-É£+ than the controls, suggesting that these cells, as well as CD4+ T lymphocytes, have crucial role of protection against M. tuberculosis. These findings have contributed to a better understanding of the immunologic changes in M. tuberculosis infection and the development of new strategies for diagnosis and prevention of tuberculosis.

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AIM: Malnutrition and infections cause immunological changes in lymphocyte subpopulations and their functionality. We evaluated the activation capacity of lymphocytes and memory cells in 10 well nourished, seven well-nourished infected and eight malnourished infected children before and after treatment. METHODS: All the children were patients in Mexico City and were less than three years of age. The expression of various cluster of differentiation (CD) cells was assessed by flow cytometry: CD45RA (naïve) and CD45RO (memory) antigens on CD4 lymphocytes and CD69 in all lymphocytes. RESULTS: Well-nourished infected children showed a higher percentage of activated T lymphocyte (T cells), CD8+ and CD4+ memory cells during the infectious phase, suggesting that the activation mechanisms were triggered by infection. T cells from malnourished infected children showed a lower percentage of activated and memory cells. The T cell population size returned to baseline during the resolution phase of the infection in well-nourished infected children, but their T, B lymphocyte and natural killer (NK) cell counts remained high. In malnourished infected children, activated NK cells counts were low before and after therapy. CONCLUSION: After therapy, malnourished infected children showed poor NK cell responses during the infection's resolution phase, suggesting a persistent malnutrition-mediated immunological deficiency.

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A single vaccination of Yellow Fever vaccines is believed to confer life-long protection. In this study, results of vaccinees who received a single dose of 17DD-YF immunization followed over 10 y challenge this premise. YF-neutralizing antibodies, subsets of memory T and B cells as well as cytokine-producing lymphocytes were evaluated in groups of adults before (NVday0) and after (PVday30-45, PVyear1-4, PVyear5-9, PVyear10-11, PVyear12-13) 17DD-YF primary vaccination. YF-neutralizing antibodies decrease significantly from PVyear1-4 to PVyear12-13 as compared to PVday30-45, and the seropositivity rates (PRNT≥2.9Log10mIU/mL) become critical (lower than 90%) beyond PVyear5-9. YF-specific memory phenotypes (effector T-cells and classical B-cells) significantly increase at PVday30-45 as compared to naïve baseline. Moreover, these phenotypes tend to decrease at PVyear10-11 as compared to PVday30-45. Decreasing levels of TNF-α(+) and IFN-γ(+) produced by CD4(+) and CD8(+) T-cells along with increasing levels of IL-10(+)CD4(+)T-cells were characteristic of anti-YF response over time. Systems biology profiling represented by hierarchic networks revealed that while the naïve baseline is characterized by independent micro-nets, primary vaccinees displayed an imbricate network with essential role of central and effector CD8(+) memory T-cell responses. Any putative limitations of this cross-sectional study will certainly be answered by the ongoing longitudinal population-based investigation. Overall, our data support the current Brazilian national immunization policy guidelines that recommend one booster dose 10 y after primary 17DD-YF vaccination.

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