Immuno Vocab 1/2 Exam 3

Autoimmunity

Humoral and cell-mediated immune responses directed toward self-antigens, causing tissue and organ damage.

Self-tolerance

Ability of the immune system to accept self-antigens and not initiate an immune response against them.

Molecular mimicry

Autoantibodies produced against foreign antigens (such as microbes or pharmaceuticals) cross-react with self-antigens.

Epitope spreading

Development of a broadening immune response to endogenous antigens released during chronic inflammation.

Superantigens

Bacterial antigens that cause a nonspecific, polyclonal activation of lymphocytes.

Systemic Lupus Erythematosus (SLE)

A chronic systemic inflammatory disease affecting multiple organ systems through polyclonal B cell activation and immune complex deposition.

Malar rash

A classic butterfly-shaped skin rash across the cheeks and bridge of the nose, occurring in 30-40% of SLE patients.

Diffuse proliferative glomerulonephritis

A very serious inflammatory kidney disease caused by immune complex deposition; it is the most common cause of death in SLE patients.

C3 nephritic factor (C3Nef)

An autoantibody that binds and stabilizes C3 convertase, leading to continuous complement activation and severely decreased C3 levels.

Rheumatoid Arthritis (RA)

A chronic autoimmune arthritis of the peripheral joints linked to the HLA-DR4 gene that can progress to joint deformity and disability.

Pannus

An abnormal sheet of vascularized granulation tissue that grows into the joint space in RA, destroying cartilage and bone.

Granulomatosis with Polyangiitis (GPA)

A rare autoimmune disease involving inflammation of small- to medium-sized blood vessels, the respiratory tract, and the kidneys.

Kawasaki Disease

Also known as mucocutaneous lymph node syndrome, a condition causing necrotizing arteritis and inflammation of medium and small arteries, particularly coronary arteries, typically seen in young children.

Antinuclear Antibodies (ANAs)

A sensitive but unspecific group of autoantibodies directed against antigens in cell nuclei, present in over 99% of lupus patients.

Anti-dsDNA

An autoantibody highly specific for SLE that correlates directly with disease activity and produces a homogeneous immunofluorescence staining pattern.

Anti-histone

The premier laboratory hallmark autoantibody characteristically associated with drug-induced lupus.

Anti-Sm (Anti-Smith)

An autoantibody highly diagnostic for lupus, present in 20-40% of patients, which displays a speckled immunofluorescence pattern.

Anti-SS-A/Ro and Anti-SS-B/La

Autoantibodies commonly positive in both SLE and Sjögren's syndrome, showing a finely speckled nuclear pattern.

Anti-RNP / Anti-RNA

Autoantibodies to ribonucleoprotein associated with scleroderma and other mixed connective tissue disorders, producing a nucleolar staining pattern.

Anti-centromere

An autoantibody showing numerous individual speckled dots in the nucleus, classically found in patients with CREST syndrome.

Anti-cardiolipin

A type of phospholipid antibody found in roughly 60% of lupus patients that can cause false-positive results on non-treponemal syphilis assays and prolong clotting times (APTT/PT).

Rheumatoid Factor (RF)

An autoantibody, usually of the IgM class, directed against the Fc portion of a patient's own IgG molecules; found in about 80% of RA cases but not specific to it.

Anti-CCP

An autoantibody directed against cyclic citrullinated peptides released by dying white blood cells, which serves as a highly specific marker for RA.

Anti-Neutrophil Cytoplasmic Antibodies (ANCA)

Autoantibodies produced against proteins inside neutrophil granules, strongly associated with systemic vascular inflammation.

c-ANCA (Cytoplasmic)

A distinct staining pattern where fluorescence is localized throughout the cytoplasm and granules of the neutrophil, typically demonstrating specificity for proteinase 3 in GPA.

p-ANCA (Perinuclear)

A less common staining pattern where fluorescence concentrates in a ring around the neutrophil nucleus.

Hashimoto's Thyroiditis

A T cell-mediated autoimmune destruction of the thyroid gland resulting in primary hypothyroidism, characterized by high TSH, low free T4, anti-TPO, and anti-Tg antibodies.

Graves' Disease

An autoimmune thyroid disease characterized by hyperthyroidism and exophthalmos, driven by thyroid receptor antibodies (TRAbs) like Thyroid-Stimulating Immunoglobulin (TSI) that continuously stimulate the TSH receptor.

Type 1 Diabetes Mellitus (T1D)

An endocrine disorder characterized by immune-mediated destruction of pancreatic beta cells, resulting in absolute insulin deficiency, hyperglycemia, and autoantibodies to GAD, IA-2, or ICA.

Celiac Disease

A small intestine inflammatory disease triggered by dietary gluten, linked to HLA-DQ2/DQ8, diagnosed preferentially using a tissue transglutaminase (tTG) IgA screening test.

Autoimmune Hepatitis (AIH)

An immune-mediated destruction of liver hepatocytes more common in females, with AIH-1 showing smooth muscle antibodies (SMA) and ANAs, and AIH-2 showing anti-LKM-1 or anti-LC-1.

Primary Biliary Cirrhosis (PBC)

An autoimmune liver disease involving the chronic destruction of intra-hepatic bile ducts and cholestasis, strongly marked by antimitochondrial antibodies (AMAs) in 90% of cases.

Multiple Sclerosis (MS)

A chronic inflammatory disorder of the central nervous system featuring plaques, destruction of the myelin sheath, and autoantibodies against myelin basic protein that appear as oligoclonal bands on CSF protein electrophoresis.

Myasthenia Gravis

A neuromuscular disorder causing muscle weakness due to autoantibodies blocking or destroying acetylcholine receptors (AChR) at the neuromuscular junction.

Anti-Glomerular Basement Membrane Disease

A severe type II hypersensitivity condition where autoantibodies target the alpha-3 chain of type IV collagen in kidney glomeruli and lung alveoli, causing a smooth, linear ribbon-like immunofluorescence pattern.

Allergy immunotherapy (AIT)

A therapeutic approach involving the gradual administration of increasing doses of an allergen to induce immune tolerance.

Wheal and flare

The characteristic positive skin reaction consisting of a central raised swelling (wheal) surrounded by redness (flare), visualized during in vivo skin testing.

Allergen-Specific IgE Testing

An in vitro laboratory assay, historically referred to as RAST, used to detect IgE levels directed against a specific allergen in patient serum.

Testing for Total IgE

An in vitro laboratory assay, historically referred to as RIST, used to measure the absolute concentration of circulating IgE, often utilized during suspected parasitic infections.

Type II Hypersensitivity

Also known as antibody-mediated cytotoxic hypersensitivity, where IgG and IgM antibodies target antigens on cell surfaces, causing complement activation, cell destruction, or altered cell function.

Antibody-dependent cell-mediated cytotoxicity (ADCC)

A mechanism of cell damage where target cells coated with IgG are actively destroyed by immune effector cells like NK cells or macrophages.

Hemolytic disease of the newborn (HDN)

An alloimmune Type II condition where a pregnant woman produces IgG antibodies against fetal red blood cell antigens, most commonly RhD.

Direct Antiglobulin Test (DAT)

A laboratory test used to detect red blood cells coated in vivo with IgG antibodies or complement pieces, utilizing poly-specific anti-human globulin.

Indirect Antiglobulin Test

A two-step laboratory method, also known as the Indirect Coombs' test, used to screen patient serum for unexpected antibodies against reagent red blood cells.

Type III Hypersensitivity

Also known as complex-mediated hypersensitivity, driven by IgG and IgM directed against soluble antigens, forming small immune complexes that precipitate out and deposit in tissues.

Arthus Reaction

A localized skin reaction caused by Type III hypersensitivity, characterized by redness, edema, and localized vascular inflammation peaking 3 to 8 hours after antigen exposure.

Serum Sickness

A generalized Type III hypersensitivity reaction caused by passive immunization with animal serum, triggering antibodies against foreign proteins and producing headache, fever, joint pain, rashes, and lymphadenopathy.

Type IV Hypersensitivity

A cell-mediated, delayed hypersensitivity response involving Th1 cells and macrophages that peaks 48 to 72 hours after antigen exposure.

Contact dermatitis

A localized Type IV skin reaction where low-molecular-weight compounds act as haptens to sensitize Th1 cells, resulting in erythema, swelling, and papules upon re-exposure.

Haptens

Small, low-molecular-weight compounds that are not immunogenic on their own and must bind to a skin protein carrier to stimulate an immune response.

Hypersensitivity pneumonitis

An allergic lung disease caused by the chronic inhalation of bacterial or fungal spores, exemplified by occupational conditions like Farmer's lung disease or bird breeder's lung disease.

Patch test

A skin test used to diagnose contact dermatitis where the suspected antigen is applied directly onto the skin surface, with a positive result showing redness, papules, or tiny blisters.

Mantoux method

A diagnostic intradermal skin test utilizing Purified Protein Derivative (PPD) to screen for tuberculosis exposure or evaluate T cell function.

Induration

A firm, raised hardening of the skin tissue that serves as the visual marker for measuring a positive Mantoux tuberculin skin test.

Interferon Gamma Release Assays (IGRA)

In vitro blood tests that measure the production of IFN-γ by patient T cells stimulated with specific Mycobacterium tuberculosis antigens.

Quantiferon TB Gold Plus assay

A specific ELISA-based IGRA variant where whole blood is incubated in specialized tubes containing MTB antigens to measure plasma IFN-γ.

T-SPOT-TB test

An ELISpot-based IGRA variant where patient mononuclear cells are incubated with MTB antigens to enumerate individual IFN-γ secreting cells.