Induction of tumor peptide-specific cytotoxic T cells under serum-free conditions by mature human dendritic cells

Tumor vaccination strategies using antigen-pulsed dendritic cells (DC) are currently under development. We established an in vitro system using cultured DC from HLA-typed volunteers for the induction of tumor peptide-specific CD8+ T cells. The strength and specificity of the resulting CTL responses were investigated. For stimulation of syngeneic CD8+ T cells two well-defined DC populations were generated: CD1a+ immature DC cultured in the presence of GM-CSF and IL-4 and mature CD83+ DC generated by additional stimulation with a cytokine cocktail. Stimulations were performed under serum-free conditions and in the absence of exogenous cytokines. Analysis of T cell responses showed that mature DC, but not immature DC, were able to induce the expansion of syngeneic tumor peptide-specific CD8+ T cells. Priming of CD8+ T cells with peptide-pulsed mature DC rapidly increased the frequency of antigen-specific T cells (ELISPOT technique). T cells induced by mature DC showed strong antigen-specific cytotoxicity in 51Cr-release assays whereas no antigen-specific cytotoxicity was detectable in CTL generated by immature DC. These data show that terminally differentiated mature DC are necessary for the induction of tumor antigen-specific CTL responses

A comparison of two types of dendritic cell as adjuvants for the induction of melanoma-specific T-cell responses in humans following intranodal injection

Dendritic cells (DCs) elicit potent anti-tumoral T-cell responses in vitro and in vivo. However, different types of DC have yet to be compared for their capacity to induce anti-tumor responses in vivo at different developmental stages. Herein, we correlated the efficiencies of different types of monocyte-derived DC as vaccines on the resulting anti-tumor immune responses in vivo. Immature and mature DCs were separately pulsed with a peptide derived from tyrosinase, MelanA/MART-1 or MAGE-1 and a recall antigen. Both DC populations were injected every 2 weeks in different lymph nodes of the same patient. Immune responses were monitored before, during and after vaccination. Mature DCs induced increased recall antigen-specific CD4( ) T-cell responses in 7/8 patients, while immature DCs did so in only 3/8. Expansion of peptide-specific IFN-gamma-producing CD8( ) T cells was observed in 5/7 patients vaccinated with mature DCs but in only 1/7 using immature DCs. However, these functional data did not correlate with the tetramer staining. Herein, immature DCs also showed expansion of peptide-specific T cells. In 2/4 patients vaccinated with mature DCs, we observed induction of peptide-specific cytotoxic T cells, as monitored by chromium-release assays, whereas immature DCs failed to induce peptide-specific cytotoxic T cells in the same patients. Instead, FCS-cultured immature DCs induced FCS-specific IgE responses in 1 patient. Our data demonstrate that this novel vaccination protocol is an efficient approach to compare different immunization strategies within the same patient. Thus, our data define FCS-free cultured mature DCs as superior inducers of T-cell responses in melanoma patients

The Relationship between COVID-19 Severity and Bacillus Calmette-Guerin (BCG)/ Mycobacterium tuberculosis exposure history in healthcare workers: a multi-center study

The COVID-19 pandemic has brought countries' health services into sharp focus. It was drawn to our group's attention that healthcare workers (HCWs) had a lower mortality rate against higher COVID-19 incidence compared to the general population in Turkey. Since risk of exposure to tuberculosis bacillus among healthcare workers are higher than the population, we aimed to investigate if there is a relationship between BCG and Mycobacterium tuberculosis exposure history with COVID-19 severity in infected HCWs. This study was conducted with 465 infected HCWs from thirty-three hospitals to assess the relationship between COVID-19 severity (according to their hospitalization status and the presence of radiological pneumonia) and BCG and Mycobacterium tuberculosis exposure history. HCWs who required hospital admission had significantly higher rates of chronic diseases, radiological pneumonia, and longer working hours in the clinics. Higher rates of history of contact and care to tuberculosis patients, history of tuberculosis, and BCG vaccine were observed in hospitalized HCWs. HCWs who had radiological pneumonia had a significantly increased ratio of history of care to tuberculosis patients and a higher family history of tuberculosis. The findings from our study suggest that the lower mortality rate despite the more severe disease course seen in infected HCWs might be due to frequent exposure to tuberculosis bacillus and the mortality-reducing effects of the BCG vaccine

Causative pathogens and antibiotic resistance in diabetic foot infections: A prospective multi-center study

WOS: 000378759700027PubMed ID: 26965794Aim: Clinical practice guidelines for the management of diabetic foot infections developed by the Infectious Diseases Society of America (IDSA) are commonly used worldwide. The issue of whether or not these guidelines need to be adjusted for local circumstances, however, has seldom been assessed in large prospective trials. Methods: The Turk-DAY trial was a prospective, multi-center study in which infectious disease specialists from centers across Turkey were invited to participate (NCT02026830). Results: A total of 35 centers throughout Turkey enrolled patients in the trial. Overall, investigators collected a total of 522 specimens from infected diabetic foot wounds for culture from 447 individual patients. Among all isolates, 36.4% were gram-positive organisms, with Staphylococcus aureus the most common among these (11.4%). Gram-negative organisms constituted 60.2% of all the isolates, and the most commonly isolated gram-negative was Escherichia coli (15%). The sensitivity rates of the isolated species were remarkably low for several antimicrobials used in the mild infection group. Conclusions: Based on our findings, several of the antimicrobials frequently used for empirical treatment, including some also recommended in the IDSA guidelines, would not be optimal for treating diabetic foot infections in Turkey. Although the IDSA guideline recommendations may be helpful to guide empiric antimicrobial therapy of DFIs, they should be adjusted to local conditions. (C) 2016 Elsevier Inc. All rights reserved