Acetylcholine receptors are responsible for binding acetylcholine, a neurotransmitter for signal transduction in CNS. They are localized in neuromuscular junctions. Antibodies against acetylcholine receptor are found in myasthenia gravis disease, which destroys the receptor function, leading to a neuromuscular transmission defect, which then causes hypofunction, fatigue, and inflammation of skeletal muscles and produces serum antibodies against muscle antigens.

Acetylcholine receptors are responsible for binding acetylcholine, a neurotransmitter for signal transduction in CNS. They are localized in neuromuscular junctions. Antibodies against acetylcholine receptor are found in myasthenia gravis disease, which destroys the receptor function, leading to a neuromuscular transmission defect, which then causes hypofunction, fatigue, and inflammation of skeletal muscles and produces serum antibodies against muscle antigens.

Actin is responsible for regulating paracellular flow across the intestinal epithelium. However, increased levels of actin suggest epithelial cell damage leading to increased intestinal permeability and decreased barrier function.

AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid) is a compound that is a specific agonist for the AMPA receptor, where it mimics the effects of the neurotransmitter glutamate. In some epilepsies, antibodies to AMPA receptors leads to neuron damage. The same is true for ischemia, where oxygen deprivation leads to excitotoxicity. Conversely, Alzheimer's disease is characterized by decreased AMPA activation and synapse loss.

Antibodies against Amphiphysin occur in patients with paraneoplastic variant Stiff person syndrome but can also be seen in autoimmune encephalitis. Antibodies against Amphiphysin are associated with breast cancer and small cell lung cancer. Neurological symptoms may precede the diagnosis of cancer with up to five years. 

Antibodies against Amphiphysin are graded as High-risk antibodies with a frequency of 80% of underlying cancer and a positive result yield 3 points PNS score, according to Updated Diagnostic Criteria for Paraneoplastic Neurologic Syndromes. 

Antibodies against Amphiphysin occur in patients with paraneoplastic variant Stiff person syndrome but can also be seen in autoimmune encephalitis. Antibodies against Amphiphysin are associated with breast cancer and small cell lung cancer. Neurological symptoms may precede the diagnosis of cancer with up to five years. 

Antibodies against Amphiphysin are graded as High-risk antibodies with a frequency of 80% of underlying cancer and a positive result yield 3 points PNS score, according to Updated Diagnostic Criteria for Paraneoplastic Neurologic Syndromes. 

Antibodies to aquaporin 4 constitute a sensitive and highly specific serum marker of neuromyelitis optica (NMO) that can facilitate the differential diagnosis of NMO and classic multiple sclerosis.

Neuromyelitis optica is an inflammatory demyelinating disorder of the central nervous system (CNS). The discovery of circulating IgG antibodies against the astrocyte water channel protein aquaporin 4 (AQP4) and the evidence that AQP4 IgG is involved in the development of neuromyelitis optica revolutionized the understanding of the disease. Anti aquaporin 4 antibodies have also been shown in patients with peripheral demyelination. In addition, human aquaporin 4 shows cross-reactivity with corn and soybean aquaporins.

Antibodies to aquaporin 4 constitute a sensitive and highly specific serum marker of neuromyelitis optica (NMO) that can facilitate the differential diagnosis of NMO and classic multiple sclerosis.

Neuromyelitis optica is an inflammatory demyelinating disorder of the central nervous system (CNS). The discovery of circulating IgG antibodies against the astrocyte water channel protein aquaporin 4 (AQP4) and the evidence that AQP4 IgG is involved in the development of neuromyelitis optica revolutionized the understanding of the disease. Anti aquaporin 4 antibodies have also been shown in patients with peripheral demyelination. In addition, human aquaporin 4 shows cross-reactivity with corn and soybean aquaporins.

Anti-Beta2 Glycoprotein I IgG is a specific class of autoantibodies directed against beta-2 glycoprotein I (β2GPI), a plasma protein that plays a critical role in the regulation of coagulation. The presence of these autoantibodies is clinically significant, particularly in autoimmune disorders such as Antiphospholipid Syndrome (APS), where they contribute to a hypercoagulable state. APS, characterized by thrombosis and pregnancy morbidity, is often associated with the presence of anti-β2GPI IgG, along with other antiphospholipid antibodies like lupus anticoagulant and anti-cardiolipin antibodies.

Anti-Beta2 Glycoprotein I IgM antibodies are a critical serological marker in the field of immunology and hematology, particularly in the diagnosis and management of antiphospholipid syndrome (APS). Beta2 Glycoprotein I, a phospholipid-binding plasma protein, plays a pivotal role in the coagulation process. The presence of IgM autoantibodies against Beta2 Glycoprotein I indicates an autoimmune response that can interfere with the normal coagulation pathway, leading to an increased risk of thrombosis. These autoantibodies are a subset of antiphospholipid antibodies, which also include anti-cardiolipin antibodies and lupus anticoagulant. In the clinical context, the detection of Anti-Beta2 Glycoprotein I IgM is significant for the diagnosis of APS, particularly in patients presenting with unexplained blood clots (thrombosis) or recurrent pregnancy loss, both of which are hallmark features of APS.

Serial testing shows that increasing amounts of IgG anti-C1q predict renal flares in SLE patients. Elevated serum titers of anti-C1q antibodies tend to be associated with proliferative forms of lupus, glomerulonephritis and subendothelial deposits of immune complexes.

Anti-Cardiolipin antibodies (aCL) of the IgA class are autoantibodies that target cardiolipin, a phospholipid found in cell membranes. While less commonly discussed than their IgG and IgM counterparts, IgA anti-cardiolipin antibodies also play a role in autoimmune conditions, particularly antiphospholipid syndrome (APS).

APS is an autoimmune disorder characterized by an increased risk of blood clots (thrombosis) and pregnancy complications, including recurrent miscarriages. The presence of IgA anti-cardiolipin antibodies can contribute to the diagnostic criteria for APS, especially in patients who test negative for the more common IgG and IgM types but have clinical symptoms suggestive of APS.

Anti-Cardiolipin antibodies (aCL) of the IgG class are a type of autoantibody directed against cardiolipin, a phospholipid present in cell membranes. These antibodies are significant in the diagnosis and management of autoimmune disorders, particularly in the context of antiphospholipid syndrome (APS).

APS is characterized by thrombosis (blood clots) and pregnancy complications, including recurrent miscarriages. The presence of anti-cardiolipin antibodies, especially the IgG subtype, is one of the laboratory criteria for diagnosing APS. Elevated levels of these antibodies can increase the risk of blood clot formation in veins and arteries, leading to complications like deep vein thrombosis, stroke, or heart attack.