Immune system

phagocytosis

In cell biology, phagocytosis (from Ancient Greek φαγεῖν (phagein) , meaning "to devour", κύτος, (kytos) , meaning "cell", and -osis, meaning "process") is the process by which a cell—often a phagocyte or a protist—engulfs a solid particle to form an internal vesicle known as a phagosome.

inflammation

Inflammation is the innate immune system response to an attack on the body. This can occur through a blunt-force or penetrating tissue injury or in response to an infection caused by a pathogen. Exposure to chemical irritants or toxins will cause inflammation, as will burns, frostbite, or other injuries. The inflammation process protects the body by isolating the damaged area, attracting immune cells and molecules to the site and, in later stages, promoting the healing of affected tissues. In fact, without inflammation, wounds or infections would never heal.

Innate response

Innate immunity refers to nonspecific defense mechanisms that come into play immediately or within hours of an antigen's appearance in the body. These mechanisms include physical barriers such as skin, chemicals in the blood, and immune system cells that attack foreign cells in the body. The innate immune response is activated by chemical properties of the antigen.

lymphocytes

Lymphocyte, type of white blood cell (leukocyte) that is of fundamental importance in the immune system because lymphocytes are the cells that determine the specificity of the immune response to infectious microorganisms and other foreign substances.

MAC

MAC proteins form rings and tunnel through the pathogen's surface membrane. In other words, the MAC puts holes in the invading cell. These holes cause the cell to leak or explode by weakening its membrane. The cell dies quickly. Killing cells by punching holes into them makes the MAC extremely potent — and also extremely destructive if it runs out of control. For this reason the MAC (and the Complement system in general) is tightly regulated by additional proteins.

monoclonal anitbody

Monoclonal antibodies represent a population of antibodies that recognize a single epitope within an antigen. They are typically produced from a single B cell of an immunized mouse, thereby generating a clonal population of antibodies, identical to one another and all recognizing the same epitope of a specific antigen. Although B cells can be used to harvest antibodies, the disadvantage is these cells have a finite lifespan and will eventually stop producing the antibody. By fusing a specific antibody-producing B cell with a myeloma cell, the limited lifespan of a B cell can be overcome. The resulting immortalized B cell-myeloma hybridoma can provide a constant supply of highly specific monoclonal antibody. Since monoclonal antibodies only recognize one epitope, they generally have low cross reactivity with non-specific antigens. Their epitope specificity, limited cross reactivity, and long term yield make monoclonal antibodies attractive for use in many biological assays and applications. - See more at: http://www.sigmaaldrich.com/life-science/cell-biology/antibodies/antibody-products.html?TablePage=14574648#sthash.ojuDOeG8.dpuf

PAMPs

Pattern recognition receptors (PRR) are a class of innate immune response-expressed proteins that respond to pathogen-associated molecular patterns (PAMP) and endogenous stress signals termed danger-associated molecular patterns (DAMP).

polyclonal antibody

Polyclonal antibodies represent a population of antibodies collected from multiple B cell clones that have been activated by the immune response of an immunized animal. Traditionally, an animal such as a goat, sheep, or rabbit is injected with a specific antigen that elicits a primary immune response. This is followed by a secondary and tertiary immunization that produces higher titers of antibody against the particular immunizing antigen. The serum containing the antibodies is collected and typically affinity purified in order to enrich for the antibodies raised against the antigen. This process ultimately lends itself to the production of high titer, high affinity polyclonal antibodies against the antigen of interest. - See more at: http://www.sigmaaldrich.com/life-science/cell-biology/antibodies/antibody-products.html?TablePage=14574648#sthash.ojuDOeG8.dpuf

PMNS

Polymorphonuclear leukocytes (PMN), or granulocytes, are a type of white blood cell. They arise from the myeloid cell line in the bone marrow and help the body to fight infection. PMNs include neutrophils, basophils and eosinophils, which circulate in the bloodstream, as well as mast cells, which reside in the tissues. Their primary role is to digest any foreign invaders.

primary lymphoid tissue

Primary lymphoid tissues are sites where lymphocytes develop from progenitor cells into functional and mature lymphocytes. The major primary lymphoid tissue is the marrow, the site where all lymphocyte progenitor cells reside and initially differentiate. This organ is discussed in Chap. 4. The other primary lymphoid tissue is the thymus, the site where progenitor cells from the marrow differentiate into mature thymus-derived (T) cells.

secondary lymphoid tissue

Secondary lymphoid tissues are sites where lymphocytes interact with each other and nonlymphoid cells to generate immune responses to antigens. These include the spleen, lymph nodes, and mucosa-associated lymphoid tissues (MALT). The structure of these tissues provides insight into how the immune system discriminates between self-antigens and foreign antigens and develops the capacity to orchestrate a variety of specific and nonspecific defenses against invading pathogens.

TLRs

Toll-like receptors (TLRs) recognize microbial products during infection and initiate signalling pathways that culminate in the increased expression of immune and inflammatory genes. TLRs that recognize nucleic acids signal from endosomes, whereas cell-surface TLRs sense lipids and proteins. Two major signalling pathways have been detailed. The core pathway activated by most TLRs leads to activation of the transcription factor nuclear factor-κB (NF-κB) and the mitogen-activated protein (MAP) kinases p38 and JNK. These signalling cascades increase the expression of many pro-inflammatory genes. The second pathway is activated by TLR3 and TLR4 and leads to activation of both NF-κB and another transcription factor interferon regulatory factor 3 (IRF3), allowing for an additional set of genes to be induced, including antiviral genes such as interferon-β (IFN-β). In this way, TLRs can tailor the innate response to pathogens.

lymph node

cluster of immune system cells

dendritic cells

endritic cells are professional antigen processing cells. They have a number of receptors that enhance the uptake of antigens, and they are specialized to convert these antigens into MHC-peptide complexes that can be recognized by lymphocytes. However, the dendritic cells need to do more than present antigens to T cells. They are also potent accessory cells that directly trigger and control responses by T cells and by all other types of lymphocytes.

anamnestic response

he anamnestic response refers to the immune response of the body to a pathogen it recognises - it produces a flood of antibodies against the pathogen. This response is possible through memory cells, that store information regarding the recognition of a pathogen based on previous interaction.

interferon

naturally occurring substance that interferes with the ability of viruses to reproduce. Interferon also boosts the immune system.

chemokines

A cytokine and a chemokine are both small proteins made by cells in the immune system. They are important in the production and growth of lymphocytes, and in regulating responses to infection or injury such as inflammation and wound healing. Cytokines are the general category of messenger molecules, while chemokines are a special type of cytokine that direct the migration of white blood cells to infected or damaged tissues. Both use chemical signals to induce changes in other cells, but the latter are specialized to cause cell movement.

b cells

A type of white blood cell and, specifically, a type of lymphocyte. Many B cells mature into what are called plasma cells that produce antibodies (proteins) necessary to fight off infections while other B cells mature into memory B cells. All of the plasma cells descended from a single B cell produce the same antibody which is directed against the antigen that stimulated it to mature. The same principle holds with memory B cells. Thus, all of the plasma cells and memory cells "remember" the stimulus that led to their formation. The maturation of B cells takes place in birds in an organ called the bursa of Fabricus. B cells in mammals mature largely in the bone marrow. The B cell, or B lymphocyte, is thus an immunologically important cell. It is not thymus-dependent, has a short lifespan, and is responsible for the production of immunoglobulins. It expresses immunoglobulins on its surface.

macrophage

A type of white blood cell that ingests foreign material. Macrophages are key players in the immune response to foreign invaders of the body, such as infectious microorganisms. They are normally found in the liver, spleen, and connective tissues of the body.

Acute

Acute inflammation occurs within minutes of an injury such as a cut, splinter, or insect bite. Or, it can take several hours to become fully activated in cases of bacterial infection, for example. But, in either case, it is a comparatively sudden, rapid, and short-term response to infection, injury, or toxic exposure.

Adaptive immunity

Adaptive immunity refers to antigen-specific immune response. The adaptive immune response is more complex than the innate. The antigen first must be processed and recognized. Once an antigen has been recognized, the adaptive immune system creates an army of immune cells specifically designed to attack that antigen. Adaptive immunity also includes a "memory" that makes future responses against a specific antigen more efficient.

antibody

An antibody (Ab), also known as an immunoglobulin (Ig), is a large Y-shape protein produced by plasma cells that is used by the immune system to identify and neutralize foreign objects such as bacteria and viruses. The antibody recognizes a unique part of the foreign target, called an antigen.

antigen

An antigen is any substance that causes your immune system to produce antibodies against it. An antigen may be a foreign substance from the environment, such as chemicals, bacteria, viruses, or pollen. An antigen may also be formed inside the body, as with bacterial toxins or tissue cells.

opsonization

Anitbody Opsonization is the process by which a pathogen (virus, fungi or bacteria that causes disease) is marked of ingestion and destruction by a phagocyte (white blood cells that protects the body by ingesting harmful foreign particles). Opsonization involves the binding of an opsonin i.e., antibody, to a receptor on the pathogen's cell membrane. Antibodies are proteins that exist in bodily fluids and are used both as a detection and response device by the immune system. After opsonin binds to the membrane, phagocytes are attracted to the pathogen. So, Opsonization is a process in which pathogens are coated with a substance called an opsonin, marking the pathogen out for destruction by the immune system.

CD4

CD4 cells are a type of white blood cell that fights infection. Another name for them is T-helper cells. CD4 cells are made in the spleen, lymph nodes, and thymus gland, which are part of the lymph or infection-fighting system. CD4 cells move throughout your body, helping to identify and destroy germs such as bacteria and viruses.

chemokines

Chemokines are cytokines that induce chemotaxis, which is the movement of a cell or group of cells that follow a chemical messenger to a new location. Unlike cytokines, chemokines have just one major role: to direct the chemotaxis of leukocytes toward foreign, potentially disease-causing microorganims so that these cells are labeled and destroyed by the immune response. Both proteins will act on system target cells, but only chemokines specifically control the chemotaxis of leukocytes during the inflammation that initiates immune response to a pathogen.

cytokines

Cytokines are a class of proteins secreted in the mammalian immune system, used as messenger molecules to control the duration and strength of the immune response to foreign microorganisms. Many cytokines produced by T cells direct the immune response of various white blood cells (leukocytes) to a foreign microorganism in the body. Among the important varieties are the interleukin (IL) molecules and interferon alpha and beta. The ILs help regulate inflammation, fever, and wound healing, among other things, while the interferons block the replication of viruses.