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Humoral Immune Deficiency
Humoral immune deficiencies are conditions which cause impairment of humoral immunity, which can lead to immunodeficiency. It can be mediated by insufficient number or function of B cells, the plasma cells they differentiate into, or the antibody secreted by the plasma cells. The most common such immunodeficiency is inherited selective IgA deficiency, occurring between 1 in 100 and 1 in 1000 persons, depending on population. They are associated with increased vulnerability to infection, but can be difficult to detect (or asymptomatic) in the absence of infection. Signs and symptoms Signs/symptoms of humoral immune deficiency depend on the cause, but generally include signs of infection such as: * Sinusitis * Sepsis * Skin infection * Pneumonia Causes Cause of this deficiency is divided into ''primary'' and ''secondary'': * ''Primary'' the International Union of Immunological Societies classifies primary immune deficiencies of the humoral system as follows: :* Absent B cells w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
B Cell
B cells, also known as B lymphocytes, are a type of the lymphocyte subtype. They function in the humoral immunity component of the adaptive immune system. B cells produce antibody molecules which may be either secreted or inserted into the plasma membrane where they serve as a part of B-cell receptors. When a naïve or memory B cell is activated by an antigen, it proliferates and differentiates into an antibody-secreting effector cell, known as a plasmablast or plasma cell. In addition, B cells Antigen presentation, present antigens (they are also classified as professional Antigen-presenting cell, antigen-presenting cells, APCs) and secrete cytokines. In mammals B cells Cellular differentiation, mature in the bone marrow, which is at the core of most bones. In birds, B cells mature in the bursa of Fabricius, a lymphoid organ where they were first discovered by Chang and Glick, which is why the ''B'' stands for ''bursa'' and not ''bone marrow'', as commonly believed. B cells, unl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Immunoglobulin Heavy Chain
The immunoglobulin heavy chain (IgH) is the large polypeptide subunit of an antibody (immunoglobulin). In the human genome, the IgH gene loci are on chromosome 14. A typical antibody is composed of two immunoglobulin (Ig) heavy chains and two Ig light chains. Several different types of heavy chain exist that define the class or isotype of an antibody. These heavy chain types vary between different animals. All heavy chains contain a series of immunoglobulin domains, usually with one variable domain (VH) that is important for binding antigen and several constant domains (CH1, CH2, etc.). Production of a viable heavy chain is a key step in B cell maturation. If the heavy chain is able to bind to a surrogate light chain and move to the plasma membrane, then the developing B cell can begin producing its light chain. The heavy chain does not always have to bind to a light chain. Pre-B lymphocytes can synthesize heavy chain in the absence of light chain, which then can allow the h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transient Hypogammaglobulinemia Of Infancy
Transient hypogammaglobulinemia of infancy is a form of hypogammaglobulinemia appearing after birth, leading to a reduction in the level of IgG, and also sometimes IgA and IgM. It can result in increased infections, but it can also present without symptoms. Signs and symptoms Allergy disorders are the second most common feature, with upper and lower respiratory tract infections accounting for the majority of cases. In addition to developmental delay and cardiac defects, rare manifestations include gastroenteritis, invasive infections, and urinary tract infections. Causes It is unknown what specifically causes infantile transient hypogammaglobulinemia. The following are some of the hypothesized mechanisms: 1) defective T cells that prevent B cells from stimulating the proper synthesis of antibodies; 2) maternal IgG suppresses the production of IgG; 3) low levels of vital cytokines; and 4) genetic variations in families predisposed to immunodeficiency. Mechanism Normally, a n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Selective Immunoglobulin A Deficiency
Selective immunoglobulin A (IgA) deficiency (SIgAD) is a kind of immunodeficiency, a type of hypogammaglobulinemia. People with this deficiency lack immunoglobulin A (IgA), a type of antibody that protects against infections of the mucous membranes lining the mouth, airways, and digestive tract. It is defined as an undetectable serum IgA level in the presence of normal serum levels of IgG and IgM, in persons older than 4 years. It is the most common of the primary antibody deficiencies. Most such persons remain healthy throughout their lives and are never diagnosed. Signs and symptoms 85–90% of IgA-deficient individuals are asymptomatic, although the reason for lack of symptoms is relatively unknown and continues to be a topic of interest and controversy.Yel, L. (2010) 'Selective IgA Deficiency', Journal of Clinical Immunology, 30(1), pp. 10-16. Some patients with IgA deficiency have a tendency to develop recurrent sinopulmonary infections, gastrointestinal infections and diso ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hyper-IgM Syndromes
Hyper IgM syndrome is a rare primary immune deficiency disorders characterized by low or absent levels of serum IgG, IgA, IgE and normal or increased levels of serum IgM. They are resulting from mutations in the pathway from B-cell activation to isotype class switching. Patients with HIGM are usually diagnosed within the first two years of life and experience severe immunosuppression. This syndrome is also known as immunoglobulin class switch recombination (Ig-CSR) deficiencies. The most common causes are mutations in the CD40 Ligand (''CD40LG'') gene located at Xq26.3-27 leading to X-linked HIGM (XHIGM) in males. Types Five types of hyper IgM syndrome have been characterized: * '' Hyper-IgM syndrome type 1'' (X-linked), characterized by mutations of the '' CD40LG'' gene. In this type, lack of CD40L on the surfaces of T cells results in defective signaling to B cells, which do not receive the needed signal to undergo isotype switching. Therefore, the only antibody secreted by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Immunoglobulin G
Immunoglobulin G (IgG) is a type of antibody. Representing approximately 75% of serum antibodies in humans, IgG is the most common type of antibody found in blood circulation. IgG molecules are created and released by plasma B cells. Each IgG antibody has two paratopes. Function Antibodies are major components of humoral immunity. IgG is the main type of antibody found in blood and extracellular fluid, allowing it to control infection of body tissues. By binding many kinds of pathogens such as viruses, bacteria, and fungi, IgG protects the body from infection. It does this through several mechanisms: * IgG-mediated binding of pathogens causes their immobilization and binding together via agglutination; IgG coating of pathogen surfaces (known as opsonization) allows their recognition and ingestion by phagocytic immune cells leading to the elimination of the pathogen itself; * IgG activates the classical pathway of the complement system, a cascade of immune protein product ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
B-cell Activating Factor
B-cell activating factor (BAFF) also known as tumor necrosis factor ligand superfamily member 13B and CD257 among other names, is a protein that in humans is encoded by the ''TNFSF13B'' gene. BAFF is also known as B Lymphocyte Stimulator (BLyS) and TNF- and APOL-related leukocyte expressed ligand (TALL-1) and the Dendritic cell-derived TNF-like molecule (CD257 antigen; cluster of differentiation 257). Structure and function BAFF is a cytokine that belongs to the tumor necrosis factor (TNF) ligand family. This cytokine is a ligand for receptors TNFRSF13B/TACI, TNFRSF17/BCMA, and TNFRSF13C/BAFF-R. This cytokine is expressed in B cell lineage cells, and acts as a potent B cell activator. It has been also shown to play an important role in the proliferation and differentiation of B cells. BAFF is a 285-amino acid long peptide glycoprotein which undergoes glycosylation at residue 124. It is expressed as a membrane-bound type II transmembrane protein on various cell types includi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tumor Necrosis Factor Receptor
The tumor necrosis factor receptor superfamily (TNFRSF) is a protein superfamily of cytokine receptors characterized by the ability to bind tumor necrosis factors (TNFs) via an extracellular cysteine-rich domain. With the exception of nerve growth factor (NGF), all TNFs are homologous to the archetypal TNF-alpha. In their active form, the majority of TNF receptors form trimeric complexes in the plasma membrane. Accordingly, most TNF receptors contain transmembrane domains (TMDs), although some can be cleaved into soluble forms (e.g. TNFR1), and some lack a TMD entirely (e.g. DcR3). In addition, most TNF receptors require specific adaptor protein such as TRADD, TRAF, RIP and FADD for downstream signalling. TNF receptors are primarily involved in apoptosis and inflammation, but they can also take part in other signal transduction pathways, such as proliferation, survival, and differentiation. TNF receptors are expressed in a wide variety of tissues in mammals, especially in leuko ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CD19
B-lymphocyte antigen CD19, also known as CD19 molecule ( Cluster of Differentiation 19), B-Lymphocyte Surface Antigen B4, T-Cell Surface Antigen Leu-12 and CVID3 is a transmembrane protein that in humans is encoded by the gene ''CD19''. In humans, CD19 is expressed in all B lineage cells. Contrary to some early doubts, human plasma cells do express CD19. CD19 plays two major roles in human B cells: on the one hand, it acts as an adaptor protein to recruit cytoplasmic signaling proteins to the membrane; on the other, it works within the CD19/ CD21 complex to decrease the threshold for B cell receptor signaling pathways. Due to its presence on all B cells, it is a biomarker for B lymphocyte development, lymphoma diagnosis and can be utilized as a target for leukemia immunotherapies. Structure In humans, CD19 is encoded by the 7.41 kilobase ''CD19'' gene located on the short arm of chromosome 16. It contains at least fifteen exons, four that encode extracellular domain ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inducible T-cell Costimulator
Inducible T-cell costimulator (also called CD278) is an immune checkpoint protein that in humans is encoded by the ''ICOS'' (Inducible T-cell COStimulator) gene. The protein belongs to the CD28 and CTLA-4 cell-surface receptor family. These are proteins expressed on the surface of immune cells that mediate signalling between them. A surface protein, the ligand, binds specifically to its receptor on another cell, leading to a signalling cascade in that cell. Function ICOS is a receptor protein expressed on the surface of activated T cells. Its ligand ICOS-L (previously called B7RP-1) is constitutively expressed on B cells. Stimulation of the ICOS receptor on T cells by ICOS-L on B cells is required for the development of follicular helper T (Tfh) cells. ICOS forms homodimers and plays an important role in cell-cell signaling, immune responses and regulation of cell proliferation. Knockout phenotype Compared to wild-type naïve T cells, ICOS-/- T cells activated with pla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Common Variable Immunodeficiency
Common variable immunodeficiency (CVID) is an inborn immune disorder characterized by recurrent infections and low antibody levels, specifically in immunoglobulin (Ig) types IgG, IgM, and IgA. Symptoms generally include high susceptibility to pathogens, chronic lung disease, as well as inflammation and infection of the gastrointestinal tract. CVID affects males and females equally. The condition can be found in children or teens but is generally not diagnosed or recognized until adulthood. The average age of diagnosis is between 20 and 50. However, symptoms vary greatly between people. "Variable" refers to the heterogeneous clinical manifestations of this disorder, which include recurrent bacterial infections, increased risk for autoimmune disease and lymphoma, as well as gastrointestinal disease.Cunningham-Rundles, C. Clinical manifestations, epidemiology, and diagnosis of common variable immunodeficiency in adults. In: UpToDate, Notarangelo, LD, Feldweg, AM (Eds), UpToDate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thymoma With Immunodeficiency
Thymoma with immunodeficiency (also known as "Good syndrome") is a rare disorder that occurs in adults in whom hypogammaglobulinemia, deficient cell-mediated immunity, and thymoma (usually benign) may develop almost simultaneously. Most reported cases are in Europe, though it occurs globally. Dr. Robert Good was first to describe the association between thymoma and hypogammaglobulinemia in 1954. Much remains to be understood about its pathogenesis. Signs and symptoms Most patients present with an immunodeficient state and recurrent sinopulmonary infections in their 4th or 5th decade of life. The immunodeficiency may occur before or after the diagnosis of a thymoma. Immunodeficiency involves both deficient humoral and cellular immunity. Patients have low total serum antibodies. The thymoma may inhibit the thymus’s normal role in production of self-tolerant T lymphocytes. These T-lymphocytes then attack the B cell precursors in the marrow, preventing maturation and ultimately ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
