China
Africa
Explore chapters and articles related to this topic
Specific Host Restance: The Effector Mechanisms
Published in Julius P. Kreier, Infection, Resistance, and Immunity, 2022
The binding of an antibody molecule to a parasite, in and of itself, does little damage to the parasite. Clumping may inhibit dispersal and bound antibody may block receptors important in the entry into host cells, but, perhaps more importantly, bound antibody can prepare the parasite for destruction by ingestion by several types of phagocytic cells. This process of preparing the parasite for ingestion is called opsonization. The word opsonin is from the Greek for “to prepare to eat.” Antibody of the IgG class is the most efficient opsonin of all the opsonic antibodies. There are numerous receptors for the Fc portion of IgG on all phagocytic cells. The two most important types of phagocytic cells are neutrophils and macrophages, with the latter possessing three different classes of Fc receptors, one of which has a very high affinity for IgG. These Fc receptors help the phagocyte bind to the antibody-coated parasite much more tightly. The receptors for the Fc portion of antibody and the receptors for complement products (such as ) function similarly on macrophages and neutrophils.
Dermal filler complications and management
Published in Michael Parker, Charlie James, Fundamentals for Cosmetic Practice, 2022
Phagocytes are a family of cells comprised of macrophages and neutrophils which engulf and digest microbes and cellular debris. By digesting unwanted bacteria and debris, the surrounding environment can be cleansed to allow for the eradication of infection and proper wound healing. Infections cause the release of cytokines which attract phagocytes to the affected area. As they migrate, macrophages differentiate and change their behaviour, some become wandering macrophages that become larger and begin to hunt down pathogens and toxic debris, whereas other macrophages will become fixed macrophages and stand guard within specific tissues to anticipate any potential spread of infection. Alongside their direct role in removing harmful pathogens and material from an area of infection, macrophages also play a key role in mediating inflammation and wound healing, as discussed previously.
Cellular Components of Blood
Published in Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal, Principles of Physiology for the Anaesthetist, 2020
Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal
The white blood cells (leukocytes) consist of two groups: (i) the phagocytes and (ii) the immunocytes. The phagocytes are made up of the granulocytes (neutrophils, eosinophils and basophils) and the monocytes. The immunocytes consist of the lymphocytes, their precursor cells and plasma cells. The phagocytes and immunocytes are important for protection against infection and are closely associated with immunoglobulins and complement.
Mechanisms of Porphyromonas gingivalis to translocate over the oral mucosa and other tissue barriers
Published in Journal of Oral Microbiology, 2023
Caroline A. de Jongh, Teun J. de Vries, Floris J. Bikker, Susan Gibbs, Bastiaan P. Krom
Periodontitis is characterized by systemic inflammation of the gingiva [52]. This attracts immune cells, among which are professional phagocytes such as monocytes and macrophages [53]. Studies have shown that macrophages are found in higher abundance in gingival biopsies of gingivitis and periodontitis patients as compared to healthy gingiva [54,55]. Professional phagocytes such as macrophages are highly specialized to engulf and destroy pathogens. However, some pathogens can evade killing by the macrophage after phagocytosis and use the macrophage as an entry into other tissues of the host. This strategy is known as a ‘Trojan Horse’ mechanism and is used by Bacillus anthracis, for example [56]. The phagocyte takes up the pathogen in the periphery (lungs, intestine or oral cavity) and travels into the bloodstream (Figure 3). Inside the phagocyte, the pathogens are protected from the host immune system and can multiply. The phagocyte will travel to another organ where the pathogen can exit the phagocyte and causes an infection in that organ. This mechanism can also lead to infection of the brain, when the phagocytes pass the blood–brain barrier [57].
Macrophages in the reticuloendothelial system inhibit early induction stages of mouse apolipoprotein A-II amyloidosis
Published in Amyloid, 2023
Hiroki Miyahara, Jian Dai, Ying Li, Xiaoran Cui, Hibiki Takeuchi, Naomi Hachiya, Fuyuki Kametani, Masahide Yazaki, Masayuki Mori, Keiichi Higuchi
Phagocytes, such as macrophages and microglial cells, are specialized cells that respond to pathogens and injury from cell debris, modified lipoproteins, protein deposits, and other harmful substrates. Although immunological pro-inflammatory responses have not been reported in peripheral systemic amyloidosis [12], immunotherapy with monoclonal antibodies against malignant plasma cells also targets and eliminates amyloid deposits from AL patients [8]. In mouse AA amyloidosis, an immunotherapeutic approach using anti-serum amyloid P component (SAP), which is an amyloid signature protein, led to the marked regression of hepatic and splenic AA deposition in mice, and this effect was eliminated by the pharmacological treatment of macrophage depletion [13]. In a rat model of hereditary amyloid polyneuropathy, a monoclonal antibody recognizing the epitope of conformationally changed TTR inhibited the progression of the disease and promoted the phagocytic activity of macrophages against aggregated TTR [14].
Bispecific antibodies for immune cell retargeting against cancer
Published in Expert Opinion on Biological Therapy, 2022
Rebecca P Chen, Kenta Shinoda, Pragya Rampuria, Fang Jin, Tin Bartholomew, Chunxia Zhao, Fan Yang, Javier Chaparro-Riggers
Phagocytosis is a cellular process that macrophages and other phagocytes utilize to engulf and internalize large particles, including pathogens and dead cells. It can be mediated by complement receptors, FcγRs, and scavenger receptors, which include a large group of cell-surface receptors that bind non-self and altered-self ligands, resulting in subsequent destruction and elimination of the internalized cell material. Importantly, FcγRs on macrophages are ligated by antibody Fc fragments to initiate antibody-dependent cellular phagocytosis (ADCP), a mechanism linking innate and adaptive immunity. Multiple preclinical models have shown that ADCP is tumoricidal, as macrophages can phagocytose antibody-opsonized tumors [154]. Phagocytosis of apoptotic cells, termed efferocytosis, resolves inflammation and dampens immune response [155].