{"id":38783,"date":"2023-06-16T02:44:00","date_gmt":"2023-06-15T20:59:00","guid":{"rendered":"https:\/\/microbenotes.com\/?p=38783"},"modified":"2023-08-03T22:01:24","modified_gmt":"2023-08-03T16:16:24","slug":"classical-pathway-of-the-complement-system","status":"publish","type":"post","link":"https:\/\/microbenotes.com\/classical-pathway-of-the-complement-system\/","title":{"rendered":"Complement System and Classical pathway"},"content":{"rendered":"\n<p>The complement system constitutes a cascade of interactions between a large number of heat-labile plasma proteins called complements. These proteins are inactively circulating in the plasma and are functional when cleaved into peptide fragments. The activation of the complement system occurs through three different pathways: the classical pathway, the mannose-binding lectin (MBL) pathway, and the alternative pathway.<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"1205\" height=\"631\" src=\"https:\/\/microbenotes.com\/wp-content\/uploads\/2022\/08\/The-Classical-pathway-of-the-complement-system.jpg\" alt=\"The Classical pathway of the complement system\" class=\"wp-image-38789\" srcset=\"https:\/\/microbenotes.com\/wp-content\/uploads\/2022\/08\/The-Classical-pathway-of-the-complement-system.jpg 1205w, https:\/\/microbenotes.com\/wp-content\/uploads\/2022\/08\/The-Classical-pathway-of-the-complement-system-300x157.jpg 300w, https:\/\/microbenotes.com\/wp-content\/uploads\/2022\/08\/The-Classical-pathway-of-the-complement-system-1024x536.jpg 1024w, https:\/\/microbenotes.com\/wp-content\/uploads\/2022\/08\/The-Classical-pathway-of-the-complement-system-768x402.jpg 768w\" sizes=\"(max-width: 1205px) 100vw, 1205px\" \/><figcaption class=\"wp-element-caption\">The Classical pathway of the complement system<\/figcaption><\/figure>\n\n\n\n<div id=\"ez-toc-container\" class=\"ez-toc-v2_0_65 counter-hierarchy ez-toc-counter ez-toc-custom ez-toc-container-direction\">\n<div class=\"ez-toc-title-container\">\n<p class=\"ez-toc-title \" >Table of Contents<\/p>\n<span class=\"ez-toc-title-toggle\"><a href=\"#\" class=\"ez-toc-pull-right ez-toc-btn ez-toc-btn-xs ez-toc-btn-default ez-toc-toggle\" aria-label=\"Toggle Table of Content\"><span class=\"ez-toc-js-icon-con\"><span class=\"\"><span class=\"eztoc-hide\" style=\"display:none;\">Toggle<\/span><span class=\"ez-toc-icon-toggle-span\"><svg style=\"fill: #0a0a0a;color:#0a0a0a\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" class=\"list-377408\" width=\"20px\" height=\"20px\" viewBox=\"0 0 24 24\" fill=\"none\"><path d=\"M6 6H4v2h2V6zm14 0H8v2h12V6zM4 11h2v2H4v-2zm16 0H8v2h12v-2zM4 16h2v2H4v-2zm16 0H8v2h12v-2z\" fill=\"currentColor\"><\/path><\/svg><svg style=\"fill: #0a0a0a;color:#0a0a0a\" class=\"arrow-unsorted-368013\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"10px\" height=\"10px\" viewBox=\"0 0 24 24\" version=\"1.2\" baseProfile=\"tiny\"><path d=\"M18.2 9.3l-6.2-6.3-6.2 6.3c-.2.2-.3.4-.3.7s.1.5.3.7c.2.2.4.3.7.3h11c.3 0 .5-.1.7-.3.2-.2.3-.5.3-.7s-.1-.5-.3-.7zM5.8 14.7l6.2 6.3 6.2-6.3c.2-.2.3-.5.3-.7s-.1-.5-.3-.7c-.2-.2-.4-.3-.7-.3h-11c-.3 0-.5.1-.7.3-.2.2-.3.5-.3.7s.1.5.3.7z\"\/><\/svg><\/span><\/span><\/span><\/a><\/span><\/div>\n<nav><ul class='ez-toc-list ez-toc-list-level-1 ' ><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-1\" href=\"https:\/\/microbenotes.com\/classical-pathway-of-the-complement-system\/#what-is-the-classical-pathway-of-the-complement-system\" title=\"What is the classical pathway of the complement system?\">What is the classical pathway of the complement system?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-2\" href=\"https:\/\/microbenotes.com\/classical-pathway-of-the-complement-system\/#stepsmechanismprocess-of-classical-pathway-of-the-complement-system\" title=\"Steps\/mechanism\/process of classical pathway of the complement system\">Steps\/mechanism\/process of classical pathway of the complement system<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-3\" href=\"https:\/\/microbenotes.com\/classical-pathway-of-the-complement-system\/#inhibitors-of-the-classical-pathway\" title=\"Inhibitors of the classical pathway\">Inhibitors of the classical pathway<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-4\" href=\"https:\/\/microbenotes.com\/classical-pathway-of-the-complement-system\/#1-soluble-regulators\" title=\"1. Soluble regulators:\">1. Soluble regulators:<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-5\" href=\"https:\/\/microbenotes.com\/classical-pathway-of-the-complement-system\/#2-membrane-bound-proteins\" title=\"2. Membrane-bound proteins:\">2. Membrane-bound proteins:<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-6\" href=\"https:\/\/microbenotes.com\/classical-pathway-of-the-complement-system\/#significanceapplications-of-classical-pathway-of-the-complement-system\" title=\"Significance\/Applications&nbsp;of classical pathway of the complement system\">Significance\/Applications&nbsp;of classical pathway of the complement system<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-7\" href=\"https:\/\/microbenotes.com\/classical-pathway-of-the-complement-system\/#references\" title=\"References\">References<\/a><\/li><\/ul><\/nav><\/div>\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"what-is-the-classical-pathway-of-the-complement-system\"><\/span><strong>What is the classical pathway of the complement system?<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>The classical pathway of the complement system is activated by the formation of antigen-antibody complexes (immune complexes). Other activators include apoptotic cells, C-reactive protein, bacterial polysaccharides, and <a href=\"https:\/\/microbenotes.com\/nucleic-acids-nucleosides-and-nucleotides\/\">nucleic acids<\/a>, which trigger classical pathways in antibody independent manner. The <a href=\"https:\/\/microbenotes.com\/complement-activation-classical-alternative-and-lectin-pathways\/\">complement proteins in this pathway<\/a> are named numerically from 1 to 9 (C1 to C9), each with subunits of their own. All the larger subunits of these proteins are designated as \u201cb\u201d and smaller subunits as \u201ca\u201d while the reverse case occurs in the case of protein C2 (C2a is a larger fragment and C2b is a smaller fragment).&nbsp;<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"stepsmechanismprocess-of-classical-pathway-of-the-complement-system\"><\/span><strong>Steps\/mechanism\/process of classical pathway of the complement system<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>The classical pathway initiates when <a href=\"https:\/\/microbenotes.com\/type-iii-immune-complex-hypersensitivity-mechanism-and-examples\/\">immune complexes<\/a> bind to the C1 complex. The pathway continues in the following described way:<\/p>\n\n\n\n<ol>\n<li>The formation of antigen-antibody complex induces a conformational change in the Fc portion of the antibody, exposing a binding site for the C1 <a href=\"https:\/\/microbenotes.com\/complement-components\/\">component of complement<\/a>. C1 protein is a macromolecular complex with the following subunits:<\/li>\n<\/ol>\n\n\n\n<p>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;1 C1q, 2 C1r, 2 C1s<\/p>\n\n\n\n<p>C1q has six subunits, each composed of three homologous chains (A, B, and C) with extended tails forming six globular heads. Each globular head acts as a binding site for antibody Fc.<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"992\" height=\"707\" src=\"https:\/\/microbenotes.com\/wp-content\/uploads\/2022\/08\/Structure-of-C1Q.jpg\" alt=\"\" class=\"wp-image-38786\" srcset=\"https:\/\/microbenotes.com\/wp-content\/uploads\/2022\/08\/Structure-of-C1Q.jpg 992w, https:\/\/microbenotes.com\/wp-content\/uploads\/2022\/08\/Structure-of-C1Q-300x214.jpg 300w, https:\/\/microbenotes.com\/wp-content\/uploads\/2022\/08\/Structure-of-C1Q-768x547.jpg 768w\" sizes=\"(max-width: 992px) 100vw, 992px\" \/><figcaption class=\"wp-element-caption\">Figure: Structure of C1Q. Image Source: <a href=\"https:\/\/www.frontiersin.org\/articles\/10.3389\/fimmu.2015.00317\/full\" target=\"_blank\" rel=\"noreferrer noopener\">Lubna Kouser et al. 2015<\/a>.<\/figcaption><\/figure>\n\n\n\n<p>C1q globular heads must bind at least two Fc sites of the antibody to maintain stable C1-antibody interaction. Antigen-bound IgM undergoes conformational change exposing at least three binding sites for C1q whereas IgG has only one binding site for C1q.<\/p>\n\n\n\n<ol start=\"2\">\n<li>As C1q binds to antibodies through its globular heads, conformational changes occur in the C1r proenzyme. The activated C1r now cleaves C1s activating C1s serine protease.&nbsp;<\/li>\n<\/ol>\n\n\n\n<ol start=\"3\">\n<li>Activated C1s tend to activate another component, C4, by cleavage. This bound C1s cleaves C4 forming C4b, which binds covalently to the bacterial surface membrane.<\/li>\n<\/ol>\n\n\n\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"1200\" height=\"1684\" src=\"https:\/\/microbenotes.com\/wp-content\/uploads\/2022\/08\/classical-pathway-of-the-complement-system.jpg\" alt=\"classical pathway of the complement system steps\" class=\"wp-image-38784\" srcset=\"https:\/\/microbenotes.com\/wp-content\/uploads\/2022\/08\/classical-pathway-of-the-complement-system.jpg 1200w, https:\/\/microbenotes.com\/wp-content\/uploads\/2022\/08\/classical-pathway-of-the-complement-system-214x300.jpg 214w, https:\/\/microbenotes.com\/wp-content\/uploads\/2022\/08\/classical-pathway-of-the-complement-system-730x1024.jpg 730w, https:\/\/microbenotes.com\/wp-content\/uploads\/2022\/08\/classical-pathway-of-the-complement-system-768x1078.jpg 768w, https:\/\/microbenotes.com\/wp-content\/uploads\/2022\/08\/classical-pathway-of-the-complement-system-1095x1536.jpg 1095w\" sizes=\"(max-width: 1200px) 100vw, 1200px\" \/><figcaption class=\"wp-element-caption\">Figure: Classical pathway of the complement system steps<\/figcaption><\/figure>\n\n\n\n<ol start=\"4\">\n<li>C4b binds C2, thereby exposing it to cleavage by C1s, forming the C4b2a enzyme complex. This enzyme complex is called C3 convertase and catalyzes the central reaction of the complement pathway. This enzyme deposits a large number of C3b molecules on the surface of the pathogen.<\/li>\n<\/ol>\n\n\n\n<ol start=\"5\">\n<li>This membrane-bound enzyme complex C4b2a3b is called C5 convertase. This enzyme in turn, cleaves C5 into C5a and C5b.<\/li>\n<\/ol>\n\n\n\n<ol start=\"6\">\n<li>C5b then triggers the formation of membrane attack complex (MAC), i.e., C5b-9. C5b attaches to C6, followed by C6 and C7 forming complex C5b-6-7, and this complex acts as a receptor for C8 and C9.&nbsp; After polymerization, finally, the MAC complex is formed.<\/li>\n<\/ol>\n\n\n\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"691\" height=\"448\" src=\"https:\/\/microbenotes.com\/wp-content\/uploads\/2022\/08\/Membrane-attack-complex-MAC.png\" alt=\"\" class=\"wp-image-38785\" srcset=\"https:\/\/microbenotes.com\/wp-content\/uploads\/2022\/08\/Membrane-attack-complex-MAC.png 691w, https:\/\/microbenotes.com\/wp-content\/uploads\/2022\/08\/Membrane-attack-complex-MAC-300x195.png 300w\" sizes=\"(max-width: 691px) 100vw, 691px\" \/><figcaption class=\"wp-element-caption\">Figure: Membrane attack complex (MAC). Image Source: <a href=\"https:\/\/link.springer.com\/chapter\/10.1007\/978-981-10-2513-6_18\" target=\"_blank\" rel=\"noreferrer noopener\">Fabiana A. Andrade et al. 2017<\/a>.<\/figcaption><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"inhibitors-of-the-classical-pathway\"><\/span><strong>Inhibitors of the classical pathway<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>The complement system must be controlled to prevent unwanted host cell attacks. Inhibitors present in host tissues are present in the soluble or membrane-bound form. Decay acceleration activity (DAA) and factor I cofactor activity (CA) are the two main regulation mechanisms that accelerate the rate of dissociation of C3 convertase and factor I-mediated cleavage of C3b-C4b incapable of reforming the C3 convertase, respectively.<\/p>\n\n\n\n<p>Some of the complement inhibitors include:<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"1-soluble-regulators\"><\/span><strong>1. Soluble regulators:<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<ul>\n<li>C1-Inhibitor (C1-INH):&nbsp; C1 is inhibited by plasma serine proteinase belonging to the serpin superfamily, also known as C1 esterase inhibitor.&nbsp;<\/li>\n\n\n\n<li>Factor I: It cleaves C3b and C4b, thus blocking the formation of C3 and C5 convertase.&nbsp;<\/li>\n\n\n\n<li>Others: C4bp, carboxypeptidase N, Factor H<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"2-membrane-bound-proteins\"><\/span><strong>2. Membrane-bound proteins:<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<ul>\n<li>CD35 (Complement receptor 1 or CR1): In humans, it is present on antigen-presenting cells, erythrocytes, etc. It accelerates the decay of the C3\/C5 convertase. It also acts as a co-factor for factor I in the degradation of C3b and C4b.<\/li>\n\n\n\n<li>CD46 (Membrane co-factor protein or MCP): It acts as a co-factor for factor I in the degradation of C3b and C4b.<\/li>\n\n\n\n<li>CD55 (Decay accelerating factor or DAF): It inhibits and accelerates the decay of C3 convertase.<\/li>\n\n\n\n<li>CD59 (protectin): It inhibits the pathway at the terminal step by inhibiting the insertion of the C9 to C5b-8 complex hence preventing MAC assembly.&nbsp;<\/li>\n\n\n\n<li>Others: CrrY<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"significanceapplications-of-classical-pathway-of-the-complement-system\"><\/span><strong>Significance\/Applications&nbsp;of classical pathway of the complement system<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<ol>\n<li>This pathway plays a key role in the opsonization and removal of nuclear debris. Bacteria and viruses are easily phagocytosed in the presence of C3b as C3b receptors are numerous on the surface of phagocytes.<\/li>\n\n\n\n<li>The small fragments C4a,3a, and C5a are important mediators of inflammation, while C2a is the precursor of vasoactive kinin.<\/li>\n\n\n\n<li>Membrane attack complex forms a pore or transmembrane channel, allowing free exchange of ions between cell and the external surrounding. The rapid influx of ions into the cell increases osmotic pressure inside the cell, which eventually bursts.<\/li>\n\n\n\n<li>Autoantibodies can also trigger this pathway leading to diseases like hemolytic anemia, myasthenia gravis, and bullous pemphigoid.&nbsp;<\/li>\n<\/ol>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"references\"><\/span><strong>References<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<ol>\n<li>Complement | NEJM<\/li>\n\n\n\n<li>Owen JA et al (2013). Kuby Immunology. 7th edition. W.H. Freeman Company. New York<\/li>\n\n\n\n<li>The complement <a href=\"https:\/\/microbenotes.com\/innate-immune-system-an-introduction\/\">system and innate immunity<\/a> &#8211; Immunobiology &#8211; NCBI Bookshelf (nih.gov)<\/li>\n\n\n\n<li>The complement system: history, pathways, cascade and inhibitors (nih.gov)<\/li>\n<\/ol>\n","protected":false},"excerpt":{"rendered":"<p>The complement system constitutes a cascade of interactions between a large number of heat-labile plasma proteins called complements. These proteins are inactively circulating in the plasma and are functional when &#8230; <a title=\"Complement System and Classical pathway\" class=\"read-more\" href=\"https:\/\/microbenotes.com\/classical-pathway-of-the-complement-system\/\" aria-label=\"Read more about Complement System and Classical pathway\">Read more<\/a><\/p>\n","protected":false},"author":23,"featured_media":38789,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1026],"tags":[1113],"custom":{"td_video":"","featured_image":"https:\/\/microbenotes.com\/wp-content\/uploads\/2022\/08\/The-Classical-pathway-of-the-complement-system.jpg","author":{"name":"Deepa Pudasaini","avatar":"https:\/\/secure.gravatar.com\/avatar\/21cf00c9bad0eaa2ce6d750168e75771?s=96&d=mm&r=g"},"categories":[{"term_id":1026,"name":"Immunology","slug":"immunology","term_group":0,"term_taxonomy_id":1026,"taxonomy":"category","description":"<strong>Immunology is an emerging branch of medical science that deals with studies related to different aspects of the immune system like the cells, structure, function, response against antigens, and disorders.<\/strong>\r\n<ul>\r\n \t<li style=\"font-weight: 400\"><span style=\"font-weight: 400\">The immune system consists of a collection of cells, chemicals, processes, and mechanisms that function to protect the body from foreign antigens, such as microbes (organisms such as bacteria, fungi, and parasites), viruses, cancer cells, and toxins.<\/span><\/li>\r\n \t<li style=\"font-weight: 400\"><span style=\"font-weight: 400\">Beyond, the structural and chemical barriers which protect us from infection, the immune system consists of two lines of defense; innate immunity and adaptive immunity.<\/span><\/li>\r\n \t<li style=\"font-weight: 400\"><span style=\"font-weight: 400\">The innate immunity represents the first line of defense against the antigen, and it is an antigen-independent defense mechanism used by the host immediately or within hours of encountering an antigen.<\/span><\/li>\r\n \t<li style=\"font-weight: 400\"><span style=\"font-weight: 400\">On the other hand, adaptive immunity is antigen-dependent and antigen-specific and, therefore, includes a lag time between exposure to the antigen and maximal response.<\/span><\/li>\r\n \t<li style=\"font-weight: 400\"><span style=\"font-weight: 400\">Studies conducted in immunology are related to the measurement of physiological functioning of the immune system in both healthy and disease conditions, malfunctioning of the system in the case of disorders, and physical, chemical, and physiological characteristics of the cells of the immune system.<\/span><\/li>\r\n \t<li style=\"font-weight: 400\"><span style=\"font-weight: 400\">Immunology is fast becoming an important branch of clinical medicine as it has a close relationship with organ transplantation, oncology, virology, bacteriology, and even dermatology.<\/span><\/li>\r\n \t<li style=\"font-weight: 400\"><span style=\"font-weight: 400\">Immunology is focused on certain organs of the body like the bone marrow and the lymphatic system and the white blood cells found in the blood.<\/span><\/li>\r\n \t<li style=\"font-weight: 400\"><span style=\"font-weight: 400\">These cells or organs producing these cells are responsible, directly or indirectly, for the defense mechanism of the body against a pathogenic agent or other antigens.<\/span><\/li>\r\n \t<li style=\"font-weight: 400\"><span style=\"font-weight: 400\">These cells keep on circulating throughout the body via blood or lymph so that they can detect antigens entering the body from different sources.<\/span><\/li>\r\n \t<li style=\"font-weight: 400\"><span style=\"font-weight: 400\">An important aspect of immunology is immunotherapy, where components of the immune system or antigens are used to treat a disease or disorder as a form of treatment.<\/span><\/li>\r\n<\/ul>","parent":0,"count":115,"filter":"raw","cat_ID":1026,"category_count":115,"category_description":"<strong>Immunology is an emerging branch of medical science that deals with studies related to different aspects of the immune system like the cells, structure, function, response against antigens, and disorders.<\/strong>\r\n<ul>\r\n \t<li style=\"font-weight: 400\"><span style=\"font-weight: 400\">The immune system consists of a collection of cells, chemicals, processes, and mechanisms that function to protect the body from foreign antigens, such as microbes (organisms such as bacteria, fungi, and parasites), viruses, cancer cells, and toxins.<\/span><\/li>\r\n \t<li style=\"font-weight: 400\"><span style=\"font-weight: 400\">Beyond, the structural and chemical barriers which protect us from infection, the immune system consists of two lines of defense; innate immunity and adaptive immunity.<\/span><\/li>\r\n \t<li style=\"font-weight: 400\"><span style=\"font-weight: 400\">The innate immunity represents the first line of defense against the antigen, and it is an antigen-independent defense mechanism used by the host immediately or within hours of encountering an antigen.<\/span><\/li>\r\n \t<li style=\"font-weight: 400\"><span style=\"font-weight: 400\">On the other hand, adaptive immunity is antigen-dependent and antigen-specific and, therefore, includes a lag time between exposure to the antigen and maximal response.<\/span><\/li>\r\n \t<li style=\"font-weight: 400\"><span style=\"font-weight: 400\">Studies conducted in immunology are related to the measurement of physiological functioning of the immune system in both healthy and disease conditions, malfunctioning of the system in the case of disorders, and physical, chemical, and physiological characteristics of the cells of the immune system.<\/span><\/li>\r\n \t<li style=\"font-weight: 400\"><span style=\"font-weight: 400\">Immunology is fast becoming an important branch of clinical medicine as it has a close relationship with organ transplantation, oncology, virology, bacteriology, and even dermatology.<\/span><\/li>\r\n \t<li style=\"font-weight: 400\"><span style=\"font-weight: 400\">Immunology is focused on certain organs of the body like the bone marrow and the lymphatic system and the white blood cells found in the blood.<\/span><\/li>\r\n \t<li style=\"font-weight: 400\"><span style=\"font-weight: 400\">These cells or organs producing these cells are responsible, directly or indirectly, for the defense mechanism of the body against a pathogenic agent or other antigens.<\/span><\/li>\r\n \t<li style=\"font-weight: 400\"><span style=\"font-weight: 400\">These cells keep on circulating throughout the body via blood or lymph so that they can detect antigens entering the body from different sources.<\/span><\/li>\r\n \t<li style=\"font-weight: 400\"><span style=\"font-weight: 400\">An important aspect of immunology is immunotherapy, where components of the immune system or antigens are used to treat a disease or disorder as a form of treatment.<\/span><\/li>\r\n<\/ul>","cat_name":"Immunology","category_nicename":"immunology","category_parent":0}]},"_links":{"self":[{"href":"https:\/\/microbenotes.com\/wp-json\/wp\/v2\/posts\/38783"}],"collection":[{"href":"https:\/\/microbenotes.com\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/microbenotes.com\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/microbenotes.com\/wp-json\/wp\/v2\/users\/23"}],"replies":[{"embeddable":true,"href":"https:\/\/microbenotes.com\/wp-json\/wp\/v2\/comments?post=38783"}],"version-history":[{"count":0,"href":"https:\/\/microbenotes.com\/wp-json\/wp\/v2\/posts\/38783\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/microbenotes.com\/wp-json\/wp\/v2\/media\/38789"}],"wp:attachment":[{"href":"https:\/\/microbenotes.com\/wp-json\/wp\/v2\/media?parent=38783"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/microbenotes.com\/wp-json\/wp\/v2\/categories?post=38783"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/microbenotes.com\/wp-json\/wp\/v2\/tags?post=38783"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}