China
Africa
Explore chapters and articles related to this topic
Host Defense and Parasite Evasion
Published in Eric S. Loker, Bruce V. Hofkin, Parasitology, 2023
Eric S. Loker, Bruce V. Hofkin
As in other infections, a key early event in the initiation of an immune response against Plasmodium is the engagement of PRRs on the surface of APCs (Figure 4.19). Upon activation, APCs secrete IL-12. Among the targets of this cytokine are NK cells. As discussed earlier, NK cells are important in the early response to intracellular pathogens, prior to the full activation of an adaptive response. Once activated, they provide an early source of IFN-γ, which serves to activate macrophages and increases their ability to kill ingested parasites as described. NK cells have also been observed to lyse Plasmodium-infected erythrocytes directly, at least in vitro, and they secrete chemokines that recruit other cells during malaria infection.
Dermal filler complications and management
Published in Michael Parker, Charlie James, Fundamentals for Cosmetic Practice, 2022
Cytotoxic T lymphocytes can be perceived as the assassins of the immunological world. Once activated, they will target and destroy cells infected with a specific pathogen. The previously discussed NK cells can target a wide range of infected cells, whereas cytotoxic T lymphocytes will only attack cells infected with pathogens they recognise. Their method of destroying infected cells is relatively similar to NK cells, with the insertion of perforin proteins, as well as pumping toxic chemicals such as granulysin and lymphotoxin to induce apoptosis within the target cell. To ensure that rogue antigens and escaping microbes are not allowed to wreak havoc elsewhere, cytotoxic T lymphocytes secrete IFN-γ, which attracts and activates phagocytes as well as macrophage migration factor to keep them at the site of infection where they are required most.
Cellular and Immunobiology
Published in Karl H. Pang, Nadir I. Osman, James W.F. Catto, Christopher R. Chapple, Basic Urological Sciences, 2021
Masood Moghul, Sarah McClelland, Prabhakar Rajan
Once cells have been activated, they attack pathogensNK cellsKill cells infected by viruses.Recognise MHC Class 1 and prevent the destruction of healthy cells.Phagocytes (e.g., neutrophils, macrophages)Dendritic cellsPhagocytic cells connect innate and adaptive immunity.Break proteins into small chains; presented to T-cells via MHC.
Engaging natural killer cells for cancer therapy via NKG2D, CD16A and other receptors
Published in mAbs, 2023
Kerry A. Whalen, Kavya Rakhra, Naveen K. Mehta, Alexander Steinle, Jennifer S. Michaelson, Patrick A. Baeuerle
Among immune cells, NK cells are most closely related to cytotoxic T cells. The latter encompasses T cell subsets, including CD8+ and CD4+ T cells, gamma-delta T cells, and natural killer T (NKT) cells, all of which contain cytotoxic granules filled with cysteine proteases, called granzymes, and a pore-forming protein called perforin. NK cells, NKT cells and gamma-delta T cells belong to the innate immune system and serve as a first line of defense against pathogens, while CD8+ and CD4+ T cells are elements of the adaptive immune system, which are highly specific for pathogenic antigens, but first need to be primed, selected, and expanded in response to peptide antigen stimuli.11 Like T cells, NK cells are cytotoxic by virtue of having secretory granules filled with the same granzymes and a variant of perforin.12 Once delivered into a cytolytic synapse formed between NK cell and target cell, perforin forms a pore in the target cell membrane that enables transmembrane delivery of granzymes. Inside the target cell, granzyme B activates pro-caspases 3 and 7, eliciting programmed cell death, or apoptosis, while other granzymes such as granzyme A, H, K and M cleave numerous other protein substrates, causing target cell damage.13 Like T cells, NK cells also release inflammatory cytokines and chemokines upon activation.14
Effective intravenous delivery of adenovirus armed with TNFα and IL-2 improves anti-PD-1 checkpoint blockade in non-small cell lung cancer
Published in OncoImmunology, 2023
Tatiana V. Kudling, James H.A. Clubb, Santeri Pakola, Dafne C.A. Quixabeira, Iris A.K. Lähdeniemi, Camilla Heiniö, Victor Arias, Riikka Havunen, Victor Cervera-Carrascon, Joao M. Santos, Eva Sutinen, Jari Räsänen, Kristian Borenius, Mikko I. Mäyränpää, Eero Aaltonen, Suvi Sorsa, Otto Hemminki, Anna Kanerva, Emmy W. Verschuren, Ilkka Ilonen, Akseli Hemminki
The immunosuppressive microenvironment is another aspect of NK cell dysfunction. Myeloid-derived suppressive cells, M2 macrophages, and T regulatory cells contribute to immune exhaustion via the expression of inhibitory ligands, suppressive cytokines, and tumor-promoting factors.43 Moreover, exclusion of functional mature dendritic cells (DCs) from NSCLC tumors and downregulation of DCs effector molecules, such as CD40, CD80, CD86, MHCII, and IL-12, which affect NK cell activity, migration, and survival.44,45 We analyzed intratumoral myeloid cells and found a higher proportion of proinflammatory M1 type macrophages and matured DCs as well as increased expression of several DCs and macrophage-secreted cytokines, boosting IFNγ production by NK cells, IL-15, IL-18, and CXCL10, in groups that received viruses. We also observed a higher percentage of macrophages expressing IRF8, which is important for myeloid cell lineage differentiation, and loss of this transcriptional factor leads to accumulation of MDCSs.46
Immunopathology of COVID-19 and its implications in the development of rhino-orbital-cerebral mucormycosis: a major review
Published in Orbit, 2022
Tarjani Vivek Dave, Akshay Gopinathan Nair, Joveeta Joseph, Suzanne K Freitag
Platelets are one of the key cells in the innate immune response. While their primary role is in hemostasis, another important role is in the immune response against pathogens, by inhibiting their dissemination through the circulation, which could increase the severity of infection.46 Platelets help in fighting microbes by producing antimicrobial peptides such as platelet factor 4.47 Typical hematologic features of COVID-19 include thrombocytopenia, lymphopenia, and neutrophilia.48 NK cells modulate the immune response that is mounted when a pathogen is encountered. There is a reduction in the number of NK cells and blunting of the effector functions of NK cells in COVID-19.46 This results in a decrease in the clearance of infected and activated cells and also results in an unabated elevation of toxic inflammatory markers.46 Previous literature has clearly shown that SARS-CoV can cause infection of the dendritic cells (DC). This can lead to an upregulation of inflammatory chemokines following a very poor antiviral cytokine expression.49,50 Dendritic cells play a prime role in specific T-cell responses, cytokine production, and antigen presentation.49 In patients with COVID-19, a loss of DC function could lead to delayed response of the immune system.