Innate lymphoid cells

Innate lymphoid cells


our bodies are in constant contact with environmental factors epithelial barriers like the skin or gut mucosa represent the first line of defense in the gut mucosa specialized immune cells actively reinforce the barrier and induce tolerance against food or commensal bacteria among these immune cells a recently discovered type of lymphocytes called innate lymphoid cells or ILCs orchestrate immune responses and maintain tissue homeostasis unlike the T and B lymphocytes ILCs do not express adaptive antigen recognition receptors as such their activation and expansion is not driven by antigen but rather by cytokine signals from the tissue ILCs come in three types by LC 1 LC 2 and IL c 3 IL c 3s interact with dendritic cells to maintain the epithelial barrier dendritic cells which are specialized in the presentation of antigen acquire antigen from the gut microbiota and secrete interleukin 23 il-23 stimulates the ILC 3 s to make IL 22 which then activates the epithelium to secrete antimicrobial peptides or a mps that kill bacteria directly il 22 also enhances il-23 production in dendritic cells this dialogue between dendritic cells and ILC 3’s maintains the barrier against pathogenic or commensal bacteria ILC 3’s also interact with macrophages to establish tolerance towards the commensal microbiota antigen from gut bacteria induces the inflammatory cytokine il-10 in macrophages which in turn triggers the secretion of gm-csf in IL c 3s gm-csf signals back to macrophages to induce retinoic acid which promotes the differentiation of regulatory t-cells regulatory t-cells are essential in maintaining tolerance towards the commensal microbiota il c2s contribute to responses against helminths these parasitic worms release enzymes that digest the mucus barrier and cause massive cell death epithelial cells sense the danger signals released by the dying cells and produce alarm ins in response to the alarm in IL 25 IL c2 s make mediators that induce mucus production from goblet cells send activated dendritic cells to the lymph node where they can prime t-cell effectors recruit eosinophils and mast cells and induce muscle contraction these actions results in the expulsion of worms from the gut in response to IL 33 il c2 s also make alpha regulan which induces tissue repair following worm clearance however ILCs also contribute to tissue pathology ILC ones which make the inflammatory mediator interferon gamma and ILC threes which can acquire the ability to make interferon gamma during chronic inflammation are found in inflammatory bowel diseases such as colitis and Crohn’s disease and contribute to gut pathology as such ALCS participates in various aspects of immunity from maintenance of the epithelial barrier and tolerance against commensals to immune responses against parasites and pathology associated with chronic inflammation you

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