Immunoglobulin E is a type of antibody that has only been found in mammals. IgE is synthesised by plasma cells. Monomers of IgE consist of two heavy chains and two light chains, with the ε chain containing 4 Ig-like constant domains. IgE's main function is immunity to parasites such as helminths like Schistosoma mansoni, Trichinella spiralis, Fasciola hepatica. IgE is utilized during immune defense against certain protozoan parasites such as Plasmodium falciparum. IgE has an essential role in type I hypersensitivity, which manifests in various allergic diseases, such as allergic asthma, most types of sinusitis, allergic rhinitis, food allergies, specific types of chronic urticaria and atopic dermatitis. IgE plays a pivotal role in responses to allergens, such as: anaphylactic drugs, bee stings, antigen preparations used in desensitization immunotherapy. Although IgE is the least abundant isotype—blood serum IgE levels in a normal individual are only 0.05% of the Ig concentration, compared to 75% for the IgGs at 10 mg/ml, which are the isotypes responsible for most of the classical adaptive immune response—it is capable of triggering the most powerful inflammatory reactions.
IgE was discovered in 1966 and 1967 by two independent groups: Kimishige Ishizaka and his wife Teruko Ishizaka at the Children's Asthma Research Institute and Hospital in Denver, by S. G. O Johansson and Hans Bennich in Sweden, their joint paper was published in April 1969. IgE primes the IgE-mediated allergic response by binding to Fc receptors found on the surface of mast cells and basophils. Fc receptors are found on eosinophils, monocytes and platelets in humans. There are two types of Fcε receptors: FcεRI, the high-affinity IgE receptor FcεRII known as CD23, the low-affinity IgE receptorIgE can upregulate the expression of both types of Fcε receptors. FcεRI is expressed on mast cells and the antigen-presenting dendritic cells in both mice and humans. Binding of antigens to IgE bound by the FcεRI on mast cells causes cross-linking of the bound IgE and the aggregation of the underlying FcεRI, leading to degranulation and the secretion of several types of type 2 cytokines like IL-3 and Stem Cell Factor which both help the mast cells survive and accumulate in tissue, IL-4, IL-5 and IL-13 as well as IL-33 which in turn activate group 2-innate lymphoid cells.
Basophils, which share a common haemopoietic progenitor with mast cells, upon the cross-linking of their surface bound IgE by antigens release type 2 cytokines like interleukin-4 and interleukin-13 and other inflammatory mediators. The low-affinity receptor is always expressed on B cells. There has been an accumulating evidence in the past decade on the physiological role of IgE: this isotype has co-evolved with basophils and mast cells in the defence against parasites like helminths but may be effective in bacterial infections. Epidemiological research shows that IgE level is increased when infected by Schistosoma mansoni, Necator americanus, nematodes in humans, it is most beneficial in removal of hookworms from the lung. Although it is not yet well understood, IgE may play an important role in the immune system’s recognition of cancer, in which the stimulation of a strong cytotoxic response against cells displaying only small amounts of early cancer markers would be beneficial. If this were the case, anti-IgE treatments such as omalizumab might have some undesirable side effects.
However, a recent study, performed based on pooled analysis using comprehensive data from 67 phase I to IV clinical trials of omalizumab in various indications, concluded that a causal relationship between omalizumab therapy and malignancy is unlikely. Atopic individuals can have up to ten times the normal level of IgE in their blood. However, this may not be a requirement for symptoms to occur as has been seen in asthmatics with normal IgE levels in their blood—recent research has shown that IgE production can occur locally in the nasal mucosa. IgE that can recognise an allergen has a unique long-lived interaction with its high-affinity receptor FcεRI so that basophils and mast cells, capable of mediating inflammatory reactions, become "primed", ready to release chemicals like histamine and certain interleukins; these chemicals cause many of the symptoms we associate with allergy, such as airway constriction in asthma, local inflammation in eczema, increased mucus secretion in allergic rhinitis, increased vascular permeability, it is presumed, to allow other immune cells to gain access to tissues, but which can lead to a fatal drop in blood pressure as in anaphylaxis.
IgE is known to be elevated in various autoimmune disorders such as Lupus, Rheumatoid Arthritis & psoriasis, is theorized to be of pathogenetic importance in RA and SLE by eliciting a hypersensitivity reaction. Regulation of IgE levels through control of B cell differentiation to antibody-secreting plasma cells is thought to involve the "low-affinity" receptor FcεRII, or CD23. CD23 may allow facilitated antigen presentation, an IgE-dependent mechanism whereby B cells expressing CD23 are able to present allergen to specific T helper cells, causing the perpetuation of a Th2 response, one of the hallmarks o
Flow cytometry is a technique used to detect and measure physical and chemical characteristics of a population of cells or particles. A sample containing cells or particles is suspended in a fluid and injected into the flow cytometer instrument; the sample is focused to ideally flow one cell at a time through a laser beam and the light scattered is characteristic to the cells and their components. Cells are labeled with fluorescent markers so that light is first absorbed and emitted in a band of wavelengths. Tens of thousands of cells can be examined and the data gathered are processed by a computer. Flow cytometry is used in basic research, clinical practice, clinical trials. Uses for flow cytometry include: Cell counting Cell sorting Determining cell characteristics and function Detecting microorganisms Biomarker detection Protein engineering detection Diagnosis of health disorders such as blood cancersA flow cytometry analyzer is an instrument that provides quantifiable data from a sample.
Other instruments using flow cytometry include cell sorters which physically separate and thereby purify cells of interest based on their optical properties. The first impedance-based flow cytometry device, using the Coulter principle, was disclosed in U. S. Patent 2,656,508, issued in 1953, to Wallace H. Coulter. Mack Fulwyler was the inventor of the forerunner to today's flow cytometers - the cell sorter. Fulwyler developed this in 1965 with his publication in Science; the first fluorescence-based flow cytometry device was developed in 1968 by Wolfgang Göhde from the University of Münster, filed for patent on 18 December 1968 and first commercialized in 1968/69 by German developer and manufacturer Partec through Phywe AG in Göttingen. At that time, absorption methods were still favored by other scientists over fluorescence methods. Soon after, flow cytometry instruments were developed, including the Cytofluorograph from Bio/Physics Systems Inc. the PAS 8000 from Partec, the first FACS instrument from Becton Dickinson, the ICP 22 from Partec/Phywe and the Epics from Coulter.
The first label-free high-frequency impedance flow cytometer based on a patented microfluidic "lab-on-chip", Ampha Z30, was introduced by Amphasys. The original name of the fluorescence-based flow cytometry technology was "pulse cytophotometry", based on the first patent application on fluorescence-based flow cytometry. At the 5th American Engineering Foundation Conference on Automated Cytology in Pensacola in 1976 - eight years after the introduction of the first fluorescence-based flow cytometer - it was agreed to use the name "flow cytometry", a term that became popular. Modern flow cytometers are able to analyze many thousand particles per second, in "real time," and, if configured as cell sorters, can separate and isolate particles with specified optical properties at similar rates. A flow cytometer is similar to a microscope, except that, instead of producing an image of the cell, flow cytometry offers high-throughput, automated quantification of specified optical parameters on a cell-by-cell basis.
To analyze solid tissues, a single-cell suspension must first be prepared. A flow cytometer has five main components: a flow cell, a measuring system, a detector, an amplification system, a computer for analysis of the signals; the flow cell has a liquid stream, which carries and aligns the cells so that they pass single file through the light beam for sensing. The measuring system use measurement of impedance and optical systems - lamps; the detector and analog-to-digital conversion system converts analog measurements of forward-scattered light and side-scattered light as well as dye-specific fluorescence signals into digital signals that can be processed by a computer. The amplification system can be logarithmic; the process of collecting data from samples using the flow cytometer is termed'acquisition'. Acquisition is mediated by a computer physically connected to the flow cytometer, the software which handles the digital interface with the cytometer; the software is capable of adjusting parameters for the sample being tested, assists in displaying initial sample information while acquiring sample data to ensure that parameters are set correctly.
Early flow cytometers were, in general, experimental devices, but technological advances have enabled widespread applications for use in a variety of both clinical and research purposes. Due to these developments, a considerable market for instrumentation, analysis software, as well as the reagents used in acquisition such as fluorescently labeled antibodies has developed. Modern instruments have multiple lasers and fluorescence detectors; the current record for a commercial instrument is 30 fluorescence detectors. Increasing the number of lasers and detectors allows for multiple antibody labeling, can more identify a target population by their phenotypic markers. Certain instruments can take digital images of individual cells, allowing for the analysis of fluorescent signal location within or on the surface of cells. Cells must pass uniformly through the center of focused laser beams to measure optical properties of cells in any flow cytometer; the purpose of the fluidic system is to move the cells one by one through the lasers beam an
A chromosome is a deoxyribonucleic acid molecule with part or all of the genetic material of an organism. Most eukaryotic chromosomes include packaging proteins which, aided by chaperone proteins, bind to and condense the DNA molecule to prevent it from becoming an unmanageable tangle. Chromosomes are visible under a light microscope only when the cell is undergoing the metaphase of cell division. Before this happens, every chromosome is copied once, the copy is joined to the original by a centromere, resulting either in an X-shaped structure if the centromere is located in the middle of the chromosome or a two-arm structure if the centromere is located near one of the ends; the original chromosome and the copy are now called sister chromatids. During metaphase the X-shape structure is called a metaphase chromosome. In this condensed form chromosomes are easiest to distinguish and study. In animal cells, chromosomes reach their highest compaction level in anaphase during chromosome segregation.
Chromosomal recombination during meiosis and subsequent sexual reproduction play a significant role in genetic diversity. If these structures are manipulated incorrectly, through processes known as chromosomal instability and translocation, the cell may undergo mitotic catastrophe; this will make the cell initiate apoptosis leading to its own death, but sometimes mutations in the cell hamper this process and thus cause progression of cancer. Some use the term chromosome in a wider sense, to refer to the individualized portions of chromatin in cells, either visible or not under light microscopy. Others use the concept in a narrower sense, to refer to the individualized portions of chromatin during cell division, visible under light microscopy due to high condensation; the word chromosome comes from the Greek χρῶμα and σῶμα, describing their strong staining by particular dyes. The term was coined by von Waldeyer-Hartz, referring to the term chromatin, introduced by Walther Flemming; some of the early karyological terms have become outdated.
For example and Chromosom, both ascribe color to a non-colored state. The German scientists Schleiden, Virchow and Bütschli were among the first scientists who recognized the structures now familiar as chromosomes. In a series of experiments beginning in the mid-1880s, Theodor Boveri gave the definitive demonstration that chromosomes are the vectors of heredity, it is the second of these principles, so original. Wilhelm Roux suggested. Boveri was able to confirm this hypothesis. Aided by the rediscovery at the start of the 1900s of Gregor Mendel's earlier work, Boveri was able to point out the connection between the rules of inheritance and the behaviour of the chromosomes. Boveri influenced two generations of American cytologists: Edmund Beecher Wilson, Nettie Stevens, Walter Sutton and Theophilus Painter were all influenced by Boveri. In his famous textbook The Cell in Development and Heredity, Wilson linked together the independent work of Boveri and Sutton by naming the chromosome theory of inheritance the Boveri–Sutton chromosome theory.
Ernst Mayr remarks that the theory was hotly contested by some famous geneticists: William Bateson, Wilhelm Johannsen, Richard Goldschmidt and T. H. Morgan, all of a rather dogmatic turn of mind. Complete proof came from chromosome maps in Morgan's own lab; the number of human chromosomes was published in 1923 by Theophilus Painter. By inspection through the microscope, he counted 24 pairs, his error was copied by others and it was not until 1956 that the true number, 46, was determined by Indonesia-born cytogeneticist Joe Hin Tjio. The prokaryotes – bacteria and archaea – have a single circular chromosome, but many variations exist; the chromosomes of most bacteria, which some authors prefer to call genophores, can range in size from only 130,000 base pairs in the endosymbiotic bacteria Candidatus Hodgkinia cicadicola and Candidatus Tremblaya princeps, to more than 14,000,000 base pairs in the soil-dwelling bacterium Sorangium cellulosum. Spirochaetes of the genus Borrelia are a notable exception to this arrangement, with bacteria such as Borrelia burgdorferi, the cause of Lyme disease, containing a single linear chromosome.
Prokaryotic chromosomes have less sequence-based structure than eukaryotes. Bacteria have a one-point from which replication starts, whereas some archaea contain multiple replication origins; the genes in prokaryotes are organized in operons, do not contain introns, unlike eukaryotes. Prokaryotes do not possess nuclei. Instead, their DNA is organized into a structure called the nucleoid; the nucleoid occupies a defined region of the bacterial cell. This structure is, dynamic and is maintained and remodeled by the actions of a range of histone-like proteins, which associate with the bacterial chromosome. In archaea, the DNA in chromosomes is more organized, with the DNA packaged within structures similar to eukaryotic nucleosomes. Certain bacteria contain plasmids or other extrachromosomal DNA; these are circular structures in the cytoplasm that contain cellular DNA and play a role in horizontal gene transfer. In prokaryotes and viruses, the DNA is densely packed and organized.
The interleukin 4 is a cytokine that induces differentiation of naive helper T cells to Th2 cells. Upon activation by IL-4, Th2 cells subsequently produce additional IL-4 in a positive feedback loop; the cell that produces IL-4, thus inducing Th2 differentiation, has not been identified, but recent studies suggest that basophils may be the effector cell. It is related and has functions similar to Interleukin 13. Interleukin 4 has many biological roles, including the stimulation of activated B-cell and T-cell proliferation, the differentiation of B cells into plasma cells, it is a key regulator in adaptive immunity. IL-4 induces B-cell class switching to IgE, up-regulates MHC class II production. IL-4 decreases the production of Th1 cells, macrophages, IFN-gamma, dendritic cell IL-12. Overproduction of IL-4 is associated with allergies. Tissue macrophages play an important role in wound repair; the presence of IL-4 in extravascular tissues promotes alternative activation of macrophages into M2 cells and inhibits classical activation of macrophages into M1 cells.
An increase in repair macrophages is coupled with secretion of IL-10 and TGF-β that result in a diminution of pathological inflammation. Release of arginase, polyaminases and TGF-β by the activated M2 cell is tied with wound repair and fibrosis; the receptor for Interleukin-4 is known as the IL-4Rα. This receptor exists in 3 different complexes throughout the body. Type 1 receptors are composed of the IL-4Rα subunit with a common γ chain and bind IL-4. Type 2 receptors consist of an IL-4Rα subunit bound to a different subunit known as IL-13Rα1; these type 2 receptors have the ability to bind both IL-4 and IL-13, two cytokines with related biological functions. IL-4 has a globular fold, stabilised by 3 disulphide bonds. One half of the structure is dominated by a 4 alpha-helix bundle with a left-handed twist; the helices are anti-parallel, with 2 overhand connections, which fall into a 2-stranded anti-parallel beta-sheet. This cytokine was co-discovered by Maureen Howard and William E. Paul as well as by Ellen Vitetta and her research group in 1982.
The nucleotide sequence for human IL-4 was isolated four years confirming its similarity to a mouse protein called B-cell stimulatory factor-1. IL-4 has been found to mediate a crosstalk between the neural stem cells and neurons that undergo neurodegeneration, initiate a regeneration cascade through phosphorylation of its intracellular effector STAT6 in an experimental Alzheimer's disease model in adult zebrafish brain. IL-4 has been shown to drive mitogenesis, dedifferentiation, metastasis in rhabdomyosarcoma. IL-4, along with other Th2 cytokines, is involved in the airway inflammation observed in the lungs of patients with allergic asthma. IL-4 plays an important role in the development of certain immune disorders allergies and some autoimmune diseases. Allergic diseases are sets of disorders that are manifested by a disproportionate response of the immune system to the allergen and Th2 responses; these pathologies include, for atopic dermatitis, asthma, or systemic anaphylaxis. Interleukin 4 mediates important pro-inflammatory functions in asthma, including induction of isotype rearrangement of IgE, expression of VCAM-1 molecules, promoting eosinophilic transmigration through endothelium, mucus secretion and T helper type 2 leading to cytokine release.
Asthma is a complex genetic disorder, associated with IL-4 gene promoter polymorphism and proteins involved in IL-4 signaling. IL-4 has a significant effect on tumor progression. Increased IL-4 production was found in breast, lung, renal cells and other types of cancer. Many overexpression of IL-4R has been found in many types of cancer. Renal cells and glioblastoma modify 10,000-13,000 receptors per cell depending on tumor type. IL-4 can primitively motivate tumor cells and increase their apoptosis resistance by increasing tumor growth. Brain tissue tumors such as astrocytoma, glioblastoma and medulloblastoma overexpress receptors for various growth factors including epidermal growth factor receptor, FGFR-1, TfR angiotensin transferrin receptor), IL-13R. Most human meningiomas massively expresses IL-4 receptors, indicating its role in cancer progression, they express IL-4Rα and IL13Rα-1-1, but not the surface γc chain, suggesting that most human meningiomas express IL-4 type II. IL-4 may play a role in the infection and development of HIV disease.
Auxiliary T-lymphocytes are a key element of HIV-1 infection. Several signs of immune dysregulation such as polyclonal B-cell initialization, previous cell-mediated antigen-induced response and hypergammaglobulinaemia occur in most HIV-1 infected patients and are associated with cytokines synthesized by Th2 cells. Increased IL-4 production by Th2 cells has been demonstrated in people infected with HIV. STAT6 Interleukin-4 at the US National Library of Medicine Medical Subject Headings Interleukin-4 from Gentaur at Gentaur Recombinant Human Interleukin-4 from Cornell University Interleukin-4 from Allergy Glossary at Health On the Net Foundation
A T cell, or T lymphocyte, is a type of lymphocyte that plays a central role in cell-mediated immunity. T cells can be distinguished from other lymphocytes, such as B cells and natural killer cells, by the presence of a T-cell receptor on the cell surface, they are called T cells. The several subsets of T cells each have a distinct function; the majority of human T cells, termed alpha beta T cells, rearrange their alpha and beta chains on the cell receptor and are part of the adaptive immune system. Specialized gamma delta T cells, have invariant T-cell receptors with limited diversity, that can present antigens to other T cells and are considered to be part of the innate immune system. Effector cells are the superset of all the various T cell types that respond to a stimulus, such as co-stimulation; this includes helper, killer and other T cell types. Memory cells are their opposite counterpart that are longer lived to target future infections as necessary. T helper cells assist other white blood cells in immunologic processes, including maturation of B cells into plasma cells and memory B cells, activation of cytotoxic T cells and macrophages.
These cells are known as CD4+ T cells because they express the CD4 glycoprotein on their surfaces. Helper T cells become activated when they are presented with peptide antigens by MHC class II molecules, which are expressed on the surface of antigen-presenting cells. Once activated, they divide and secrete small proteins called cytokines that regulate or assist in the active immune response; these cells can differentiate into one of several subtypes, including TH1, TH2, TH3, TH17, TH9, or TFH, which secrete different cytokines to facilitate different types of immune responses. Signalling from the APC directs T cells into particular subtypes. Cytotoxic T cells destroy virus-infected cells and tumor cells, are implicated in transplant rejection; these cells are known as CD8+ T cells since they express the CD8 glycoprotein at their surfaces. These cells recognize their targets by binding to antigen associated with MHC class I molecules, which are present on the surface of all nucleated cells. Through IL-10, other molecules secreted by regulatory T cells, the CD8+ cells can be inactivated to an anergic state, which prevents autoimmune diseases.
Antigen-naïve T cells expand and differentiate into memory and effector T cells after they encounter their cognate antigen within the context of an MHC molecule on the surface of a professional antigen presenting cell. Appropriate co-stimulation must be present at the time of antigen encounter for this process to occur. Memory T cells were thought to belong to either the effector or central memory subtypes, each with their own distinguishing set of cell surface markers. Subsequently, numerous new populations of memory T cells were discovered including tissue-resident memory T cells, stem memory TSCM cells, virtual memory T cells; the single unifying theme for all memory T cell subtypes is that they are long-lived and can expand to large numbers of effector T cells upon re-exposure to their cognate antigen. By this mechanism they provide the immune system with "memory" against encountered pathogens. Memory T cells may be either CD4+ or CD8+ and express CD45RO. Memory T cell subtypes: Central memory T cells express CD45RO, C-C chemokine receptor type 7, L-selectin.
Central memory T cells have intermediate to high expression of CD44. This memory subpopulation is found in the lymph nodes and in the peripheral circulation.. Effector memory T cells lack expression of CCR7 and L-selectin, they have intermediate to high expression of CD44. These memory T cells lack lymph node-homing receptors and are thus found in the peripheral circulation and tissues. TEMRA stands for terminally differentiated effector memory cells re-expressing CD45RA, a marker found on naive T cells. Tissue resident memory T cells occupy tissues without recirculating. One cell surface marker, associated with TRM is the integrin αeβ7. Virtual memory T cells differ from the other memory subsets in that they do not originate following a strong clonal expansion event. Thus, although this population as a whole is abundant within the peripheral circulation, individual virtual memory T cell clones reside at low frequencies. One theory is. Although CD8 virtual memory T cells were the first to be described, it is now known that CD4 virtual memory cells exist.
Regulatory T cells are crucial for the maintenance of immunological tolerance. Their major role is to shut down T cell-mediated immunity toward the end of an immune reaction and to suppress autoreactive T cells that escaped the process of negative selection in the thymus. Suppressor T cells along with Helper T cells can collectively be called Regulatory T cells due to their regulatory functions. Two major classes of CD4 + Treg cells have been described -- FOXP3 − Treg cells. Regulatory T cells can develop either during normal development in the thymus, are known as thymic Treg cells, or can be induced peripherally and are called peripherally derived Treg cel
Reed–Sternberg cells are distinctive, giant cells found with light microscopy in biopsies from individuals with Hodgkin's lymphoma. They are derived from B lymphocytes, classically considered crippled germinal center B cells, meaning they have not undergone hypermutation to express their antibody. Seen against a sea of B cells, they give the tissue a moth-eaten appearance. Reed–Sternberg cells are large and are either multinucleated or have a bilobed nucleus with prominent eosinophilic inclusion-like nucleoli. Reed–Sternberg cells are CD30 and CD15 positive negative for CD20 and CD45; the presence of these cells is necessary in the diagnosis of Hodgkin's lymphoma – the absence of Reed–Sternberg cells has high negative predictive value. The presence of these cells is confirmed by use of biomarkers in immunohistochemistry, they can be found in reactive lymphadenopathy and rarely in other types of non-Hodgkin lymphomas. Anaplastic large cell lymphoma may show RS-like cells as well, they are named after Dorothy Reed Mendenhall and Carl Sternberg, who provided the first definitive microscopic descriptions of Hodgkin's disease.
A special type of Reed–Sternberg cells is the lacunar histiocyte, whose cytoplasm retracts when fixed in formalin, so the nuclei give the appearance of cells that lie with empty spaces between them. These are characteristic of the nodular sclerosis subtype of Hodgkin's lymphoma. Mummified RSCs are associated with classical Hodgkin's lymphoma while popcorn cells are lymphohistiocytic variant of Reed Sternberg cells and are associated with nodular lymphocyte predominant Hodgkin's lymphoma. RSCs and one RSC cell line but not other RSC cell lines express high levels of ALOX15 or ALOX15B, enzymes that metabolize arachidonic acid and various other polyunsaturated fatty acids to a wide array of bioactive products including in particular those of the 15-Hydroperoxyeicosatetraenoic acid family of arachidonic acid metabolites; this is unusual in that lymphocytes express little or no ALOX15. It is suggested that ALOX15 and/or ALOX15B operating through one of its arachidonic acid-derived products, the eoxins, contributes to the development and/or morphology of Hodgkin's lymphoma.
Non-Hodgkin lymphoma Hodgkin's lymphoma