Systemic Vasculitis: A heterogeneous group of diseases characterized by inflammation and necrosis of the blood vessel walls.Vasculitis: Inflammation of any one of the blood vessels, including the ARTERIES; VEINS; and rest of the vasculature system in the body.Polyarteritis Nodosa: A form of necrotizing non-granulomatous inflammation occurring primarily in medium-sized ARTERIES, often with microaneurysms. It is characterized by muscle, joint, and abdominal pain resulting from arterial infarction and scarring in affected organs. Polyarteritis nodosa with lung involvement is called CHURG-STRAUSS SYNDROME.Antibodies, Antineutrophil Cytoplasmic: Autoantibodies directed against cytoplasmic constituents of POLYMORPHONUCLEAR LEUKOCYTES and/or MONOCYTES. They are used as specific markers for GRANULOMATOSIS WITH POLYANGIITIS and other diseases, though their pathophysiological role is not clear. ANCA are routinely detected by indirect immunofluorescence with three different patterns: c-ANCA (cytoplasmic), p-ANCA (perinuclear), and atypical ANCA.Churg-Strauss Syndrome: Widespread necrotizing angiitis with granulomas. Pulmonary involvement is frequent. Asthma or other respiratory infection may precede evidence of vasculitis. Eosinophilia and lung involvement differentiate this disease from POLYARTERITIS NODOSA.Wegener Granulomatosis: A multisystemic disease of a complex genetic background. It is characterized by inflammation of the blood vessels (VASCULITIS) leading to damage in any number of organs. The common features include granulomatous inflammation of the RESPIRATORY TRACT and kidneys. Most patients have measurable autoantibodies (ANTINEUTROPHIL CYTOPLASMIC ANTIBODIES) against neutrophil proteinase-3 (WEGENER AUTOANTIGEN).Retinal Vasculitis: Inflammation of the retinal vasculature with various causes including infectious disease; LUPUS ERYTHEMATOSUS, SYSTEMIC; MULTIPLE SCLEROSIS; BEHCET SYNDROME; and CHORIORETINITIS.Myeloblastin: A polymorphonuclear leukocyte-derived serine protease that degrades proteins such as ELASTIN; FIBRONECTIN; LAMININ; VITRONECTIN; and COLLAGEN. It is named for its ability to control myeloid cell growth and differentiation.Anti-Neutrophil Cytoplasmic Antibody-Associated Vasculitis: Group of systemic vasculitis with a strong association with ANCA. The disorders are characterized by necrotizing inflammation of small and medium size vessels, with little or no immune-complex deposits in vessel walls.Arteritis: INFLAMMATION of any ARTERIES.Mucocutaneous Lymph Node Syndrome: An acute, febrile, mucocutaneous condition accompanied by swelling of cervical lymph nodes in infants and young children. The principal symptoms are fever, congestion of the ocular conjunctivae, reddening of the lips and oral cavity, protuberance of tongue papillae, and edema or erythema of the extremities.Vasculitis, Leukocytoclastic, Cutaneous: Disorder characterized by a vasculitic syndrome associated with exposure to an antigen such as a drug, infectious agent, or other foreign or endogenous substance. Its pathophysiology includes immune complex deposition and a wide range of skin lesions. Hypersensitivity or allergy is present in some but not all cases.Purpura, Schoenlein-Henoch: A systemic non-thrombocytopenic purpura caused by HYPERSENSITIVITY VASCULITIS and deposition of IGA-containing IMMUNE COMPLEXES within the blood vessels throughout the body, including those in the kidney (KIDNEY GLOMERULUS). Clinical symptoms include URTICARIA; ERYTHEMA; ARTHRITIS; GASTROINTESTINAL HEMORRHAGE; and renal involvement. Most cases are seen in children after acute upper respiratory infections.Microscopic Polyangiitis: A primary systemic vasculitis of small- and some medium-sized vessels. It is characterized by a tropism for kidneys and lungs, positive association with anti-neutrophil cytoplasmic antibodies (ANCA), and a paucity of immunoglobulin deposits in vessel walls.Cogan Syndrome: A condition consisting of inflammatory eye disease usually presenting as interstitial KERATITIS, vestibuloauditory dysfunction, and large- to medium-vessel vasculitis.Cryoglobulinemia: A condition characterized by the presence of abnormal quantities of CRYOGLOBULINS in the blood. Upon cold exposure, these abnormal proteins precipitate into the microvasculature leading to restricted blood flow in the exposed areas.Vasculitis, Central Nervous System: Inflammation of blood vessels within the central nervous system. Primary vasculitis is usually caused by autoimmune or idiopathic factors, while secondary vasculitis is caused by existing disease process. Clinical manifestations are highly variable but include HEADACHE; SEIZURES; behavioral alterations; INTRACRANIAL HEMORRHAGES; TRANSIENT ISCHEMIC ATTACK; and BRAIN INFARCTION. (From Adams et al., Principles of Neurology, 6th ed, pp856-61)Autoantibodies: Antibodies that react with self-antigens (AUTOANTIGENS) of the organism that produced them.Peroxidase: A hemeprotein from leukocytes. Deficiency of this enzyme leads to a hereditary disorder coupled with disseminated moniliasis. It catalyzes the conversion of a donor and peroxide to an oxidized donor and water. EC 1.11.1.7.Behcet Syndrome: Rare chronic inflammatory disease involving the small blood vessels. It is of unknown etiology and characterized by mucocutaneous ulceration in the mouth and genital region and uveitis with hypopyon. The neuro-ocular form may cause blindness and death. SYNOVITIS; THROMBOPHLEBITIS; gastrointestinal ulcerations; RETINAL VASCULITIS; and OPTIC ATROPHY may occur as well.Serine Endopeptidases: Any member of the group of ENDOPEPTIDASES containing at the active site a serine residue involved in catalysis.Immunoglobulins, Intravenous: Immunoglobulin preparations used in intravenous infusion, containing primarily IMMUNOGLOBULIN G. They are used to treat a variety of diseases associated with decreased or abnormal immunoglobulin levels including pediatric AIDS; primary HYPERGAMMAGLOBULINEMIA; SCID; CYTOMEGALOVIRUS infections in transplant recipients, LYMPHOCYTIC LEUKEMIA, CHRONIC; Kawasaki syndrome, infection in neonates, and IDIOPATHIC THROMBOCYTOPENIC PURPURA.Otorhinolaryngologic Diseases: Pathological processes of the ear, the nose, and the throat, also known as the ENT diseases.Autoimmune Diseases: Disorders that are characterized by the production of antibodies that react with host tissues or immune effector cells that are autoreactive to endogenous peptides.Glomerulonephritis: Inflammation of the renal glomeruli (KIDNEY GLOMERULUS) that can be classified by the type of glomerular injuries including antibody deposition, complement activation, cellular proliferation, and glomerulosclerosis. These structural and functional abnormalities usually lead to HEMATURIA; PROTEINURIA; HYPERTENSION; and RENAL INSUFFICIENCY.Immunosuppressive Agents: Agents that suppress immune function by one of several mechanisms of action. Classical cytotoxic immunosuppressants act by inhibiting DNA synthesis. Others may act through activation of T-CELLS or by inhibiting the activation of HELPER CELLS. While immunosuppression has been brought about in the past primarily to prevent rejection of transplanted organs, new applications involving mediation of the effects of INTERLEUKINS and other CYTOKINES are emerging.Autoantigens: Endogenous tissue constituents that have the ability to interact with AUTOANTIBODIES and cause an immune response.Giant Cell Arteritis: A systemic autoimmune disorder that typically affects medium and large ARTERIES, usually leading to occlusive granulomatous vasculitis with transmural infiltrate containing multinucleated GIANT CELLS. The TEMPORAL ARTERY is commonly involved. This disorder appears primarily in people over the age of 50. Symptoms include FEVER; FATIGUE; HEADACHE; visual impairment; pain in the jaw and tongue; and aggravation of pain by cold temperatures. (From Adams et al., Principles of Neurology, 6th ed)Prednisolone: A glucocorticoid with the general properties of the corticosteroids. It is the drug of choice for all conditions in which routine systemic corticosteroid therapy is indicated, except adrenal deficiency states.Neutrophils: Granular leukocytes having a nucleus with three to five lobes connected by slender threads of chromatin, and cytoplasm containing fine inconspicuous granules and stainable by neutral dyes.Collagen Diseases: Historically, a heterogeneous group of acute and chronic diseases, including rheumatoid arthritis, systemic lupus erythematosus, progressive systemic sclerosis, dermatomyositis, etc. This classification was based on the notion that "collagen" was equivalent to "connective tissue", but with the present recognition of the different types of collagen and the aggregates derived from them as distinct entities, the term "collagen diseases" now pertains exclusively to those inherited conditions in which the primary defect is at the gene level and affects collagen biosynthesis, post-translational modification, or extracellular processing directly. (From Cecil Textbook of Medicine, 19th ed, p1494)Skin Diseases, Vascular: Skin diseases affecting or involving the cutaneous blood vessels and generally manifested as inflammation, swelling, erythema, or necrosis in the affected area.Rheumatoid Vasculitis: Necrotizing VASCULITIS of small and medium size vessels, developing as a complication in RHEUMATOID ARTHRITIS patients. It is characterized by peripheral vascular lesions, cutaneous ULCERS, peripheral GANGRENE, and MONONEURITIS MULTIPLEX.Leukemia, Myelomonocytic, Chronic: A myelodysplastic-myeloproliferative disease characterized by monocytosis, increased monocytes in the bone marrow, variable degrees of dysplasia, but an absence of immature granulocytes in the blood.Methylprednisolone: A PREDNISOLONE derivative with similar anti-inflammatory action.Cyclophosphamide: Precursor of an alkylating nitrogen mustard antineoplastic and immunosuppressive agent that must be activated in the LIVER to form the active aldophosphamide. It has been used in the treatment of LYMPHOMA and LEUKEMIA. Its side effect, ALOPECIA, has been used for defleecing sheep. Cyclophosphamide may also cause sterility, birth defects, mutations, and cancer.Enzyme-Linked Immunosorbent Assay: An immunoassay utilizing an antibody labeled with an enzyme marker such as horseradish peroxidase. While either the enzyme or the antibody is bound to an immunosorbent substrate, they both retain their biologic activity; the change in enzyme activity as a result of the enzyme-antibody-antigen reaction is proportional to the concentration of the antigen and can be measured spectrophotometrically or with the naked eye. Many variations of the method have been developed.Immunoglobulin G: The major immunoglobulin isotype class in normal human serum. There are several isotype subclasses of IgG, for example, IgG1, IgG2A, and IgG2B.Lupus Erythematosus, Systemic: A chronic, relapsing, inflammatory, and often febrile multisystemic disorder of connective tissue, characterized principally by involvement of the skin, joints, kidneys, and serosal membranes. It is of unknown etiology, but is thought to represent a failure of the regulatory mechanisms of the autoimmune system. The disease is marked by a wide range of system dysfunctions, an elevated erythrocyte sedimentation rate, and the formation of LE cells in the blood or bone marrow.Respiratory Burst: A large increase in oxygen uptake by neutrophils and most types of tissue macrophages through activation of an NADPH-cytochrome b-dependent oxidase that reduces oxygen to a superoxide. Individuals with an inherited defect in which the oxidase that reduces oxygen to superoxide is decreased or absent (GRANULOMATOUS DISEASE, CHRONIC) often die as a result of recurrent bacterial infections.Arthritis, Rheumatoid: A chronic systemic disease, primarily of the joints, marked by inflammatory changes in the synovial membranes and articular structures, widespread fibrinoid degeneration of the collagen fibers in mesenchymal tissues, and by atrophy and rarefaction of bony structures. Etiology is unknown, but autoimmune mechanisms have been implicated.Retrospective Studies: Studies used to test etiologic hypotheses in which inferences about an exposure to putative causal factors are derived from data relating to characteristics of persons under study or to events or experiences in their past. The essential feature is that some of the persons under study have the disease or outcome of interest and their characteristics are compared with those of unaffected persons.Fluorescent Antibody Technique, Indirect: A form of fluorescent antibody technique commonly used to detect serum antibodies and immune complexes in tissues and microorganisms in specimens from patients with infectious diseases. The technique involves formation of an antigen-antibody complex which is labeled with fluorescein-conjugated anti-immunoglobulin antibody. (From Bennington, Saunders Dictionary & Encyclopedia of Laboratory Medicine and Technology, 1984)Glucocorticoids: A group of CORTICOSTEROIDS that affect carbohydrate metabolism (GLUCONEOGENESIS, liver glycogen deposition, elevation of BLOOD SUGAR), inhibit ADRENOCORTICOTROPIC HORMONE secretion, and possess pronounced anti-inflammatory activity. They also play a role in fat and protein metabolism, maintenance of arterial blood pressure, alteration of the connective tissue response to injury, reduction in the number of circulating lymphocytes, and functioning of the central nervous system.Kidney Diseases: Pathological processes of the KIDNEY or its component tissues.Antibodies, Monoclonal: Antibodies produced by a single clone of cells.Treatment Outcome: Evaluation undertaken to assess the results or consequences of management and procedures used in combating disease in order to determine the efficacy, effectiveness, safety, and practicability of these interventions in individual cases or series.Antibody Specificity: The property of antibodies which enables them to react with some ANTIGENIC DETERMINANTS and not with others. Specificity is dependent on chemical composition, physical forces, and molecular structure at the binding site.Biological Markers: Measurable and quantifiable biological parameters (e.g., specific enzyme concentration, specific hormone concentration, specific gene phenotype distribution in a population, presence of biological substances) which serve as indices for health- and physiology-related assessments, such as disease risk, psychiatric disorders, environmental exposure and its effects, disease diagnosis, metabolic processes, substance abuse, pregnancy, cell line development, epidemiologic studies, etc.Endothelium, Vascular: Single pavement layer of cells which line the luminal surface of the entire vascular system and regulate the transport of macromolecules and blood components.Drug Therapy, Combination: Therapy with two or more separate preparations given for a combined effect.Severity of Illness Index: Levels within a diagnostic group which are established by various measurement criteria applied to the seriousness of a patient's disorder.Tumor Necrosis Factor-alpha: Serum glycoprotein produced by activated MACROPHAGES and other mammalian MONONUCLEAR LEUKOCYTES. It has necrotizing activity against tumor cell lines and increases ability to reject tumor transplants. Also known as TNF-alpha, it is only 30% homologous to TNF-beta (LYMPHOTOXIN), but they share TNF RECEPTORS.Kidney: Body organ that filters blood for the secretion of URINE and that regulates ion concentrations.Cytoplasm: The part of a cell that contains the CYTOSOL and small structures excluding the CELL NUCLEUS; MITOCHONDRIA; and large VACUOLES. (Glick, Glossary of Biochemistry and Molecular Biology, 1990)Case-Control Studies: Studies which start with the identification of persons with a disease of interest and a control (comparison, referent) group without the disease. The relationship of an attribute to the disease is examined by comparing diseased and non-diseased persons with regard to the frequency or levels of the attribute in each group.Cryoglobulins: Abnormal immunoglobulins, especially IGG or IGM, that precipitate spontaneously when SERUM is cooled below 37 degrees Celsius. It is characteristic of CRYOGLOBULINEMIA.Follow-Up Studies: Studies in which individuals or populations are followed to assess the outcome of exposures, procedures, or effects of a characteristic, e.g., occurrence of disease.Polymorphism, Genetic: The regular and simultaneous occurrence in a single interbreeding population of two or more discontinuous genotypes. The concept includes differences in genotypes ranging in size from a single nucleotide site (POLYMORPHISM, SINGLE NUCLEOTIDE) to large nucleotide sequences visible at a chromosomal level.Purpura: Purplish or brownish red discoloration, easily visible through the epidermis, caused by hemorrhage into the tissues. When the size of the discolorization is >2-3 cm it is generally called Ecchymoses (ECCHYMOSIS).Genetic Predisposition to Disease: A latent susceptibility to disease at the genetic level, which may be activated under certain conditions.