Frequency of IRF5+ dendritic cells is associated with the TLR7-induced inflammatory cytokine response in SARS-CoV-2 infection.

The SARS-CoV-2 infection leads to enhanced inflammation driven by innate immune responses. Upon TLR7 stimulation, dendritic cells (DC) mediate the production of inflammatory cytokines, and in particular of type I interferons (IFN). Especially in DCs, IRF5 is a key transcription factor that regulates pathogen-induced immune responses via activation of the MyD88-dependent TLR signaling pathway.

High-resolution analysis of individual spike peptide-specific CD4 T-cell responses in vaccine recipients and COVID-19 patients.

Objectives: Potential differences in the breadth, distribution and magnitude of CD4 T-cell responses directed against the SARS-CoV-2 spike glycoprotein between vaccinees, COVID-19 patients and subjects who experienced both ways of immunisation have not been comprehensively compared on a peptide level.

Methods: Following virus-specific cultivation, we determined the T-cell responses directed against 253 individual overlapping 15-mer peptides covering the entire SARS-CoV-2 spike glycoprotein using IFN-γ ELISpot and intracellular cytokine staining. HLA binding was determined for selected peptides.

High and Sustained Ex Vivo Frequency but Altered Phenotype of SARS-CoV-2-Specific CD4 T-Cells in an Anti-CD20-Treated Patient with Prolonged COVID-19.

Here, we longitudinally assessed the ex vivo frequency and phenotype of SARS-CoV-2 membrane protein (aa145-164) epitope-specific CD4 T-cells of an anti-CD20-treated patient with prolonged viral positivity in direct comparison to an immunocompetent patient through an MHC class II DRB1*11:01 Tetramer analysis. We detected a high and stable SARS-CoV-2 membrane-specific CD4 T-cell response in both patients, with higher frequencies of virus-specific CD4 T-cells in the B-cell-depleted patient. However, we found an altered virus-specific CD4 T-cell memory phenotype in the B-cell-depleted patient that was skewed towards late differentiated memory T-cells, as well as reduced frequencies of SARS-CoV-2-specific CD4 T-cells with CD45RA CXCR5 PD-1 circulating T follicular helper cell (cT) phenotype.

Deciphering the Plasmodium falciparum malaria-specific CD4+ T-cell response: ex vivo detection of high frequencies of PD-1+TIGIT+ EXP1-specific CD4+ T cells using a novel HLA-DR11-restricted MHC class II tetramer.

Relatively little is known about the ex vivo frequency and phenotype of the Plasmodium falciparum-specific CD4+ T-cell response in humans. The exported protein 1 (EXP1) is expressed by plasmodia at both, the liver stage and blood stage, of infection making it a potential target for CD4+ and CD8+ effector T cells. Here, a fluorochrome-labelled HLA-DRB1∗11:01-restriced MHC class II tetramer derived from the P.

Increased frequency of TIGITCD73-CD8 T cells with a TOX TCF-1low profile in patients with newly diagnosed and relapsed AML.

The inhibitory receptor TIGIT, as well as theectonucleotidases CD39 and CD73 constitute potential exhaustion markers for T cells. Detailed analysis of these markers can shed light into dysregulation of the T-cell response in acute myeloid leukemia (AML) and will help to identify potential therapeutic targets.  The phenotype and expression of transcription factors was assessed on different T-cell populations derived from peripheral blood (PB, = 38) and bone marrow (BM, = 43).