Immune System

Anti-thyroid peroxidase (anti-TPO) antibodies are immune proteins that target thyroid peroxidase, a key enzyme in thyroid hormone production. Their presence often signals an autoimmune reaction against the thyroid gland.

Measures antibodies against acetylcholine receptors, often used to help diagnose myasthenia gravis.

Measures autoantibodies against the La (SS-B) protein, used to help diagnose Sjögren's syndrome and other connective tissue diseases.

Anti-CCP is an autoantibody directed against citrullinated proteins. It is a highly specific marker for rheumatoid arthritis and aids in diagnosis and prognosis.

Anti-GBM antibodies target the glomerular basement membrane in kidneys and sometimes lungs. They are central to Goodpasture syndrome, a rare autoimmune disease causing kidney damage and lung bleeding.

An autoantibody test targeting the GAD65 enzyme in pancreatic beta cells, used primarily to diagnose and distinguish type 1 diabetes.

A screening test for exposure to the hepatitis C virus; a positive result requires further testing to confirm active infection.

Autoantibodies against intrinsic factor, a stomach protein required for vitamin B12 absorption; their presence is associated with pernicious anemia.

Cardiolipin IgM antibodies are autoantibodies that target cardiolipin, a phospholipid involved in blood clotting. They are tested to help diagnose antiphospholipid syndrome (APS).

Anti-CCP antibodies are autoantibodies targeting citrullinated proteins, highly specific for rheumatoid arthritis. The FEIA method provides precise measurement.

Anti-fodrin IgG antibodies are autoantibodies targeting the structural protein alpha-fodrin. They are often measured to help diagnose Sjögren's syndrome, especially when classic antibodies are absent.

Intrinsic factor antibodies are autoantibodies that attack the protein needed for vitamin B12 absorption. Their presence is a key marker for pernicious anemia, an autoimmune cause of vitamin B12 deficiency.

Anti-neutrophil cytoplasmic antibodies (ANCA) are autoantibodies that target certain proteins inside white blood cells called neutrophils.

Anti-beta-2 glycoprotein I IgG antibodies are autoantibodies that target a protein involved in regulating blood clotting, often measured in the evaluation of antiphospholipid syndrome (APS).

Detects IgM autoantibodies against beta-2 glycoprotein I, a protein involved in blood clotting regulation. These antibodies are associated with antiphospholipid syndrome (APS), which raises the risk of blood clots and pregnancy complications.

The antistreptolysin O (ASO) titer measures antibodies your body produces against streptolysin O, a toxin from group A Streptococcus bacteria.

AP-50 is a blood test that evaluates the functional activity of the alternative complement pathway, a key part of the innate immune system.

Basophils are a type of granulocyte, a white blood cell involved in allergic reactions and immune defense, releasing histamine and other mediators.

Basophils are a type of white blood cell involved in allergic reactions and immune defense. The absolute basophil count measures the number of basophils in the blood, helping assess immune system health and detect certain conditions.

Borrelia IgM antibodies are immune proteins produced in response to Borrelia burgdorferi, the bacteria that causes Lyme disease. Their presence typically signals a recent or active infection.

High‑sensitivity C‑reactive protein (hs‑CRP) is a blood test that measures very low levels of CRP, a protein made by the liver in response to inflammation. It is primarily used to help evaluate the risk of future cardiovascular events.

C3 complement is a protein central to the immune system's complement cascade. It helps destroy pathogens and trigger inflammation. Measuring blood C3 levels aids in diagnosing infections, autoimmune disorders, and kidney disease.

Complement C4 is a protein involved in the immune system’s complement cascade, helping to clear pathogens and trigger inflammation.

Autoantibodies targeting centromere proteins, used as a diagnostic marker for limited systemic sclerosis and other autoimmune conditions.

Chlamydia pneumoniae IgG antibodies indicate past exposure or persistent infection with the bacterium Chlamydia pneumoniae, which causes respiratory illnesses.

CMV IgG measures antibodies that indicate past exposure to cytomegalovirus. A positive result generally means lifelong immunity in healthy people.

CMV IgM is an antibody that appears early in CMV infection. A positive result can indicate a recent or reactivated infection, but false positives are possible.

C-reactive protein (CRP) is an acute-phase protein produced by the liver. It is measured to detect and monitor inflammation in the body.

Measures autoantibodies against the CXCR3 chemokine receptor, which is found on activated immune cells. The test helps evaluate immune dysregulation in suspected autoimmune disorders.

Anti-dsDNA antibodies are autoantibodies targeting double-stranded DNA, primarily associated with systemic lupus erythematosus (SLE). Quantitative measurement aids in diagnosis and monitoring disease activity.

EBV EA p138 IgG is an antibody against a specific early antigen of the Epstein-Barr virus. Its presence indicates a past EBV infection and may be seen in some reactivation cases.

Detects IgG antibodies against the p54 early antigen of Epstein-Barr virus, indicating a past infection or a later stage of immune response to EBV.

EA p54 IgM detects IgM antibodies against an early antigen of Epstein-Barr virus (EBV), indicating acute or recent infection.

EBNA1 IgG measures IgG antibodies to EBV nuclear antigen 1, indicating past or prior EBV infection and lifelong immunity.

Detects IgG antibodies against the viral capsid antigen of Epstein-Barr virus (EBV), used to determine past or recent EBV infection status.

EBV VCA IgM antibodies appear early in Epstein-Barr virus infection and help detect recent or active infection, such as infectious mononucleosis.

Anti-centromere antibodies are autoantibodies that target centromeres in cell nuclei. They are often measured when autoimmune diseases, especially limited systemic sclerosis (CREST syndrome), are suspected.

Anti-Jo-1 antibody is an autoantibody that targets a specific nuclear antigen, often associated with inflammatory muscle diseases like polymyositis and dermatomyositis.

Anti-RNP/Sm antibodies are autoantibodies targeting ribonucleoprotein and Smith antigens, often found in systemic lupus erythematosus (SLE) and mixed connective tissue disease (MCTD).

Anti-Scl-70 antibodies are autoantibodies that target topoisomerase I, a nuclear enzyme. They are primarily associated with systemic sclerosis (scleroderma).

Anti-Sm antibodies are autoantibodies that target Smith (Sm) proteins, a component of the cell nucleus. They are highly specific for systemic lupus erythematosus (SLE).

Anti-SS-B (La) antibodies are autoantibodies directed against the La/SS-B nuclear protein; they are strongly associated with Sjögren’s syndrome and often appear together with anti-SS-A antibodies.

Endomysial antibodies are autoantibodies that target the connective tissue surrounding muscle fibers; their presence is a key indicator of celiac disease.

Eosinophils are a type of white blood cell involved in allergic responses and defense against parasites. The eosinophil percentage reflects their relative amount in your white blood cell count.

The absolute eosinophil count quantifies the number of eosinophils in a specific volume of blood, offering a more precise measure of these immune cells than the percentage alone.

Free kappa light chains are fragments of antibodies produced by plasma cells. They are measured to diagnose and monitor conditions like multiple myeloma and amyloidosis.

Free lambda light chains are a type of antibody fragment produced by plasma cells. Measuring them helps detect and monitor conditions such as multiple myeloma and other plasma cell disorders.

DGP-IgA is an antibody test that detects immune reactions to deamidated gliadin, a component of gluten. It serves as a marker for celiac disease, especially when used with tTG-IgA.

Measures IgG antibodies against deamidated gliadin peptides to aid celiac disease diagnosis, particularly useful when IgA testing is unreliable.

Hepatitis B surface antibody (Anti-HBs) measures immunity to hepatitis B virus, either from vaccination or past infection.

HSV-1/2 IgA antibodies are immunoglobulin A antibodies against herpes simplex virus types 1 and 2, measured in blood or mucosal secretions to assess recent or active infection.

HSV-1/2 IgG antibodies are immunoglobulin G antibodies against herpes simplex viruses types 1 and 2, measured in blood to determine past exposure or immune status.

Intestinal fatty acid binding protein (I-FABP) is a protein released into the blood when the cells lining the small intestine are damaged. It serves as an early marker of intestinal mucosal injury.

The absolute immature granulocyte (IG) count measures the number of young white blood cell precursors in the blood, which can signal infection, inflammation, or bone marrow response.

Immature granulocytes (IG) are young white blood cells that normally stay in the bone marrow; their presence in blood can signal infection or bone marrow stress.

IgG1 is the most abundant subclass of IgG antibodies, playing a crucial role in defending against bacteria and viruses.

IgG2 is an antibody subclass critical for defending against encapsulated bacteria like pneumococci. It is measured to evaluate immune competence.

IgG3 is a fast-responding antibody subclass that targets viruses and bacteria. Testing helps evaluate immune function and recurrent infections.

Immunoglobulin G4 (IgG4) is a subclass of IgG antibodies. This test measures its blood level, which may be elevated in certain chronic inflammatory conditions.

Immunoglobulin A (IgA) is the main antibody in mucosal surfaces, protecting against pathogens. It is measured to assess immune function and screen for certain disorders.

Immunoglobulin E (IgE) is an antibody involved in allergic reactions and defense against parasites. It is measured to help diagnose allergies and monitor immune-related conditions.

Immunoglobulin G (IgG) is the most abundant antibody in blood and extracellular fluid, playing a central role in protecting the body against infections.

Immunoglobulin M (IgM) is the largest antibody and the first one produced in response to an infection, playing a key role in the body's early immune defense.

The virus-specific T-cell ELISpot quantifies the number of circulating T cells that produce interferon-gamma after stimulation with viral antigens, reflecting cellular immune competence against viruses.

Interferon-gamma (IFN-γ) measured in an IGRA test helps detect tuberculosis infection by assessing immune cell response to TB-specific antigens.

Interleukin-1 beta (IL-1β) is a pro-inflammatory cytokine involved in immune responses, fever, and inflammation. Measuring IL-1β helps assess inflammatory conditions.

Interleukin-6 (IL-6) is a cytokine that promotes inflammation and is involved in immune response and tissue repair. It is measured to assess inflammatory states, infections, and certain chronic diseases.

Interleukin-17A (IL-17A) is a pro-inflammatory cytokine that plays a key role in immune defense, particularly against fungal and bacterial infections, and is involved in chronic inflammatory and autoimmune conditions.

Interleukin-4 (IL-4) is a cytokine involved in immune system regulation, particularly in antibody production and allergic responses. Testing IL-4 levels may help evaluate immune function and inflammatory conditions.

Measures autoantibodies against histidyl-tRNA synthetase, a marker for inflammatory muscle diseases like polymyositis.

Complement CH50 tests the overall activity of the classical complement pathway, part of the innate immune system, helping to identify complement deficiencies or consumption.

Leukotrienes are lipid mediators produced by immune cells that contribute to inflammation, bronchoconstriction, and allergic reactions. Testing is specialized, often in urine or bronchoalveolar lavage, and lacks standardized reference ranges.

Leukocytes, or white blood cells, are immune cells that help defend the body against infections and foreign substances. A leukocyte count measures the total number of these cells in a blood sample.

The absolute lymphocyte count quantifies lymphocytes, a type of white blood cell that plays a central role in the immune system by fighting infections and diseases.

M3 muscarinic acetylcholine receptor autoantibodies (M3-AChR-Ab) target a specific subtype of muscarinic receptor found on smooth muscle and glands. Their presence is associated with autoimmune conditions like Sjögren’s syndrome and can contribute to dryness symptoms.

Monocytes are a type of white blood cell that helps fight infection and regulate immunity. The monocyte relative percentage measures the proportion of monocytes among all white blood cells.

The absolute monocyte count tells you the number of circulating monocytes per volume of blood. It is used alongside the relative percentage to assess immune status and diagnose disease.

Neopterin is a substance produced by immune cells during activation, used to monitor cellular immune responses, inflammation, and certain diseases.

Neutrophils are the most abundant white blood cells, forming a critical part of the innate immune defense against bacteria and fungi. The relative count shows the percentage of neutrophils among all white cells.

The absolute neutrophil count (ANC) measures the total number of neutrophils per microliter of blood. It is a key indicator of the body’s immediate defense against bacterial and fungal infections.

Anti-nucleosome antibodies are autoantibodies that target nucleosomes (DNA-histone complexes). They are primarily associated with systemic lupus erythematosus (SLE) and drug-induced lupus.

Proteinase 3 antibodies (PR3-ANCA) are autoantibodies targeting the proteinase 3 enzyme in neutrophils. They are primarily linked to granulomatosis with polyangiitis (GPA), a form of systemic vasculitis.

Measures the ratio of two types of antibody light chains (kappa and lambda) in the blood to assess immune system balance and screen for plasma cell disorders.

Rheumatoid factor (RF) is an autoantibody that can mistakenly attack the body's own tissues. It is primarily measured to help diagnose rheumatoid arthritis and other autoimmune disorders.

Rheumatoid factor (RF-IgM) is an autoantibody that targets the body's own antibodies. It is primarily measured to help diagnose and monitor rheumatoid arthritis and other autoimmune conditions.

Quantitative measurement of anti-Scl-70 (anti-topoisomerase I) autoantibodies, which are often elevated in systemic sclerosis, particularly the diffuse form.

Anti-Smith (Sm) antibodies are autoantibodies directed against Sm proteins, highly specific for systemic lupus erythematosus (SLE).

Soluble intercellular adhesion molecule-1 (sICAM-1) is a protein released during inflammation; its blood level reflects endothelial activation and systemic inflammatory activity.

SSA antibodies, also known as anti-Ro antibodies, are autoantibodies targeting Ro ribonucleoproteins. Quantitative testing measures their concentration to aid in diagnosing autoimmune disorders such as Sjögren’s syndrome and systemic lupus erythematosus.

SSB antibodies, also known as anti-La antibodies, are autoantibodies against the La phosphoprotein involved in RNA processing. Quantitative testing helps evaluate autoimmune conditions, often together with SSA antibodies.

Tetanus toxoid antibodies are immune proteins measured to assess protection against tetanus, typically after vaccination or prior exposure. The test guides the need for booster immunization.

Thyroglobulin antibodies (TgAb) are autoantibodies targeting thyroglobulin, a key protein in thyroid hormone production. Their measurement helps identify autoimmune thyroid conditions.

Thyroglobulin is a protein made by thyroid cells; it serves as a precursor for thyroid hormones and is used as a tumor marker after thyroid cancer treatment.

Thyroglobulin antibodies (TgAb) are proteins made by the immune system that mistakenly target thyroglobulin, a key thyroid protein. Measuring TgAb helps detect autoimmune thyroid disorders like Hashimoto's thyroiditis or Graves' disease.

TNF-alpha is a signaling protein (cytokine) produced by immune cells that plays a central role in inflammation. Testing measures its concentration in the blood to assess inflammatory activity.

The Toxoplasma IgG test detects antibodies to Toxoplasma gondii, indicating past infection and usually lifelong immunity to the parasite.

The toxoplasmosis IgM test is a serologic assay that measures IgM antibodies against Toxoplasma gondii, helping to identify recent or acute infections.

The TPHA test is a serologic assay that detects antibodies against Treponema pallidum, aiding in the diagnosis of current or past syphilis infection.

Tissue transglutaminase IgA (tTG-IgA) is an autoantibody test used primarily to screen for celiac disease, an autoimmune reaction to gluten.

Transglutaminase IgG (tTG-IgG) is an antibody measured to aid in the diagnosis of celiac disease, particularly when IgA deficiency is present.

Tryptase is an enzyme released by mast cells, often measured to evaluate allergic reactions and mast cell disorders.

TRAb are autoantibodies that target the thyroid-stimulating hormone (TSH) receptor on thyroid cells. They are primarily measured to diagnose and monitor Graves' disease and distinguish it from other causes of hyperthyroidism.

U1 RNP antibodies are autoantibodies directed against the U1 ribonucleoprotein complex. This test helps diagnose mixed connective tissue disease (MCTD) and systemic lupus erythematosus (SLE).

VCA p18 IgG is an antibody test that indicates a past infection with the Epstein-Barr virus (EBV), the cause of infectious mononucleosis (mono). It is used to assess whether your immune system has previously encountered the virus.

Measures IgM antibodies against the p18 component of the Epstein-Barr virus (EBV) viral capsid antigen. It helps determine if you have a current or recent EBV infection, often causing mononucleosis.

Measures IgM antibodies against the p23 protein of Epstein-Barr virus (EBV), indicating a recent or acute infection.

VZV IgM antibodies indicate a recent or ongoing infection with the varicella-zoster virus, the cause of chickenpox and shingles. This test helps diagnose acute VZV infection.

VZV IgA is a class of antibodies produced against the varicella-zoster virus, typically measured to help diagnose acute or reactivated infections such as chickenpox or shingles.

Varicella-Zoster Virus IgG (VZV IgG) is a blood test that detects antibodies to the virus causing chickenpox and shingles. It helps determine immunity from past infection or vaccination.

Measures IgG antibodies to Epstein-Barr virus, mainly indicating a past infection.

Detects IgM antibodies to EBV, typically signaling a recent or current acute infection.