Tolerance and Autoimmune Disorders

Autoimmune diseases are chronic, often progressive, have overlapping clinical manifestations, and may target either cellular or organ-specific self-antigens.

Grave's disease affects the thyroid gland and Type 1 Diabetes Mellitus affects the pancreas.

Systemic autoimmune diseases affect multiple organs and systems throughout the body, while organ-specific diseases target a specific organ.

<p>Age, hormones, and environmental factors can all influence the presentation of autoimmune diseases.</p> Signup and view all the answers

<p>Autoreceptor antibodies, such as those found in Myasthenia gravis, interfere with normal receptor function leading to muscle weakness.</p> Signup and view all the answers

<p>Immune responses in autoimmune diseases often target self-antigens, leading to tissue damage.</p> Signup and view all the answers

<p>Classification is difficult due to similar symptoms presented by various types and overlapping clinical manifestations.</p> Signup and view all the answers

<p>They may display symptoms from each disease simultaneously, complicating their clinical picture.</p> Signup and view all the answers

<p>An example is autoimmune hemolytic anemia, where antibodies destroy red blood cells.</p> Signup and view all the answers

<p>Systemic Lupus Erythematosus may cause fatigue and joint pain, while Rheumatoid Arthritis may lead to joint swelling and stiffness.</p> Signup and view all the answers

<p>Immunologic tolerance is the inability of the immune system to mount a response against specific antigens, essential for preventing autoimmunity and maintaining homeostasis.</p> Signup and view all the answers

<p>Central tolerance involves the clonal deletion of autoreactive lymphocytes during development in the thymus or bone marrow, while peripheral tolerance regulates or eliminates these cells after they have entered circulation.</p> Signup and view all the answers

<p>Anergy is the irreversible functional inactivation of autoreactive T and B lymphocytes that escape central tolerance, preventing them from functioning and causing autoimmunity.</p> Signup and view all the answers

<p>Costimulatory molecules on APCs are essential for breaking T cell anergy, leading to the activation of T cells specific for self-antigens.</p> Signup and view all the answers

<p>Regulatory T cells suppress autoreactive lymphocytes primarily through the secretion of cytokines like IL-10, which inhibit their activation.</p> Signup and view all the answers

<p>Molecular mimicry occurs when microbial antigens share amino acid sequences with self-antigens, leading to cross-reactivity and autoimmune responses.</p> Signup and view all the answers

<p>Antigen sequestration involves hiding self-antigens behind blood-tissue barriers, such as those in the brain and eyes, preventing autoreactive lymphocytes from engaging with them.</p> Signup and view all the answers

<p>HLA-B27 is strongly associated with ankylosing spondylitis, increasing the risk of developing the disease by 100-200 times.</p> Signup and view all the answers

<p>Key factors include genetic predisposition, environmental triggers such as infections, and inherited susceptibility genes that disrupt tolerance mechanisms.</p> Signup and view all the answers

<p>The failure of self-tolerance can result in autoimmune diseases, where the immune system incorrectly targets and attacks the body's own tissues.</p> Signup and view all the answers

<p>Viral infections can modify self-antigens, induce cross-reaction with shared epitopes, and cause necrosis and inflammation that promotes autoimmunity.</p> Signup and view all the answers

<p>Traumatic injury can expose previously sequestered antigens to autoreactive lymphocytes, potentially triggering an autoimmune response as the immune system mistakenly recognizes these antigens as foreign.</p> Signup and view all the answers

<p>Sequestered self-antigens are released due to tissue trauma or inflammatory destruction, exposing hidden epitopes.</p> Signup and view all the answers

<p>Polyclonal B cell activation occurs when microorganisms stimulate multiple B cell clones, some of which may be autoreactive.</p> Signup and view all the answers

<p>The development of autoimmune diseases often involves a combination of genetic susceptibility and environmental factors, like infections, that trigger immune responses against self-antigens.</p> Signup and view all the answers

<p>Mutations in apoptosis genes can lead to a failure in deleting autoreactive lymphocytes, resulting in autoimmune lymphoproliferative disorders characterized by uncontrolled immune cell proliferation.</p> Signup and view all the answers

<p>Genetic factors, including mutations in apoptotic pathways and familial patterns of incidence, contribute significantly to the susceptibility of autoimmune diseases.</p> Signup and view all the answers

<p>Defective development of regulatory T cells can impair tolerance in the immune system, facilitating autoimmune disease progression.</p> Signup and view all the answers

<p>Inflammatory destruction can lead to tissue injury, which reveals cryptic epitopes previously hidden from the immune system.</p> Signup and view all the answers

<p>Antibodies produced against streptococcal proteins can cross-react with myocardial proteins, leading to myocarditis.</p> Signup and view all the answers