The Humoral Immune Response (HIR) is the aspect of immunity that is mediated by secreted antibodies (as opposed to cell-mediated immunity which involves T lymphocytes) produced in the cells of the B lymphocyte lineage (B cell). Immunity is a material term that describes a state of having sufficient biological defenses to avoid Infection, Disease, or other unwanted biological invasion Antibodies (also known as immunoglobulins, abbreviated Ig) are Gamma globulin Proteins that are found in Blood or other Bodily Cell-mediated immunity is an Immune response that does not involve Antibodies or complement but rather involves the activation of Macrophages A lymphocyte is a type of White blood cell in the Vertebrate Immune system. B cells are Lymphocytes that play a large role in the humoral immune response (as opposed to the cell-mediated immune response, which is governed by Secreted antibodies bind to antigens on the surfaces of invading microbes (such as viruses or bacteria), which flags them for destruction. An antigen (from antibody-generating) or immunogen is a substance that prompts the generation of Antibodies and can cause an immune response ^[1] Humoral immunity is called as such, because it involves substances found in the humours, or body fluids. Humorism, or humoralism, was a theory of the makeup and workings of the human body adopted by Greek and Roman physicians and philosophers

The study of the molecular and cellular components that comprise the immune system, including their function and interaction, is the central science of immunology. An immune system is a collection of mechanisms within an Organism that protects against Disease by identifying and killing Pathogens and Tumor Immunology is a broad branch of biomedical Science that covers the study of all aspects of the Immune system in all Organisms It deals with The immune system is divided into a more primitive innate immune system, and acquired or adaptive immune system of vertebrates, the latter of which is further divided into humoral and cellular components. Immune system|Adaptive immune systemThe innate immune system comprises the cells and mechanisms that defend the host from infection by other organisms in a non-specific manner Immune system|Passive immunity|Innate immune system The adaptive immune system is composed of highly specialized systemic cells and processes that eliminate or prevent Pathogenic Cell-mediated immunity is an Immune response that does not involve Antibodies or complement but rather involves the activation of Macrophages

Humoral immunity refers to antibody production, and the accessory processes that accompany it, including: Th2 activation and cytokine production, germinal center formation and isotype switching, affinity maturation and memory cell generation. T helper cells (also known as effector T cells or Th cells) are a sub-group of Lymphocytes (a type of White blood cell or Cytokines are a category of signalling Proteins and Glycoproteins that like Hormones and Neurotransmitters, are used extensively in cellular Germinal centres (GC are areas within Lymph nodes where B lymphocytes rapidly divide and are an important part of the humoral immune response. In Immunology, affinity maturation is the process by which B-cells produce Antibodies with increased affinity for Antigen during the course of It also refers to the effector functions of antibody, which include pathogen and toxin neutralization, classical complement activation, and opsonin promotion of phagocytosis and pathogen elimination. An effector is a molecule (originally referring to small molecules but now encompassing any regulatory molecule includes proteins that binds to a Protein and thereby alters The complement system is a Biochemical cascade that helps clear Pathogens from an organism An opsonin is any molecule that acts as a binding Enhancer for the process of Phagocytosis, for example by coating the negatively-charged molecules on the membrane Phagocytosis is the cellular process of engulfing solid particles by the Cell membrane to form an internal Phagosome, or "food vacuole ^[2]

Contents 1 History 2 Complement system 3 Antibodies 4 B cells 5 See also 6 References 7 Further reading

History

The concept of humoral immunity developed based on analysis of antibacterial activity of the components of serum. Antiseptics (from Greek αντί - anti, '"against" + σηπτικός - septikos, "putrefactive" are antimicrobial Hans Buchner is credited with the development of the humoral theory. Hans Buchner (b October 26 1483 in Ravensburg; d March 1538 probably in Konstanz) was an important German Organist and Composer ^[3] In 1890 he described alexins, or “protective substances”, which exist in the serum and other bodily fluids and are capable of killing microorganisms. Alexins, later redefined "complement" by Paul Ehrlich, were shown to be the soluble components of the innate response that lead to a combination of cellular and humoral immunity, and bridged the features of innate and acquired immunity. Paul Ehrlich ( March 14, 1854 &ndash August 20, 1915) was a German Scientist who won the 1908 Nobel Solubility is the characteristic Physical property referring to the ability of a given substance the Solute, to dissolve in a Solvent. ^[3]

Following the 1888 discovery of diphtheria and tetanus, Emil von Behring and Shibasaburo Kitasato showed that disease need not be caused by microorganisms themselves. Diphtheria ( Greek διφθερα ( diphthera)—“pair of leather scrolls" is an upper respiratory tract illness characterized by sore Tetanus is a medical condition that is characterized by a prolonged contraction of Skeletal muscle fibres Emil Adolf von Behring ( March 15, 1854 &ndash March 31, 1917) was a German Physiologist who received the 1901 was a Japanese Physician and bacteriologist. He is remembered as the co-discoverer of the infectious agent of Bubonic plague in Hong Kong in They discovered that cell-free filtrates were sufficient to cause disease. In 1890, filtrates of diphtheria (later named diphtheria toxins) were used to immunize animals in an attempt to demonstrate that immunized serum contained an antitoxin that could neutralize the activity of the toxin and could transfer immunity to non immune animals. Diphtheria toxin is an Exotoxin secreted by Corynebacterium diphtheriae, the Pathogen bacterium that causes Diphtheria. Vaccination is the administration of Antigenic material (the Vaccine) to produce immunity to a disease An antitoxin is an Antibody with the ability to neutralize a specific Toxin. ^[4] In 1897, Paul Ehrlich showed that antibodies form against the plant toxins ricin and abrin, and proposed that these antibodies are responsible for immunity. Ricin (ˈraɪ sɨn is a Protein Toxin that is extracted from the castor bean ( Ricinus communis) Abrin is a natural Poison that is found in the seeds of a plant called the Rosary pea or Jequirity pea ^[3] Ehrlich, with his friend Emil von Behring, went on to develop the diphtheria antitoxin, which became the first major success of modern immunotherapy. Immunotherapy in medicine refers to an array of treatment strategies based upon the concept of modulating the Immune system to achieve a prophylactic and/or ^[4] The presence and specificity of antibodies became the major tool for standardizing the state of immunity and identifying the presence of previous infections. Immunity is a material term that describes a state of having sufficient biological defenses to avoid Infection, Disease, or other unwanted biological invasion ^[4]

Major discoveries in the study of humoral immunity^[4]

Substance	Activity	Discovery
Alexin(s) Complement	Soluble components in the serum that are capable of killing microorganisms	Buchner (1890), Ehrlich (1892)[3]
Antitoxins	Substances in the serum that can neutralize the activity of toxins, enabling passive immunization	von Bhering and Kitasato (1890)[5]
Bacteriolysins	Serum substances that work with the complement proteins to induce bacterial lysis	Richard Pfeiffer (1895)[6]
Bacterial agglutinins & precipitins	Serum substances that agglutinate bacteria and precipitate bacterial toxins	von Gruber and Durham (1896),[7] Kraus (1897)[8]
Hemolysins	Serum substances that work with complement to lyse red blood cells	Belfanti and Carbone (1898)[9] Jules Bordet (1899)[10]
Opsonins	serum substances that coat the outer membrane of foreign substances and enhance the rate of phagocytosis by macrophages	Wright and Douglas (1903)[11]
Antibody	formation (1900), antigen-antibody binding hypothesis (1938), produced by B cells (1948), structure (1972), immunoglobulin genes (1976)	Founder: P Ehrlich[3]

Complement system

Main article: Complement system

The complement system is a biochemical cascade of the immune system that helps clear pathogens from an organism. The complement system is a Biochemical cascade that helps clear Pathogens from an organism An antitoxin is an Antibody with the ability to neutralize a specific Toxin. Passive immunity is the transfer of active Humoral immunity in the form of readymade antibodies from one individual to another Richard Friedrich Johannes Pfeiffer ( March 27, 1858 &ndash September 15 1945) was a German Physician and Bacteriologist Agglutinin is a protein found in Cow 's milk Because agglutinin clumps cow's milk requires Homogenization in order to remain smooth A precipitin is an Antibody which can Precipitate out of a solution Max von Gruber ( July 6, 1853 &ndash September 16, 1927) was an Austrian Scientist. Hemolysis is the breakdown of Red blood cells. The ability of bacterial colonies to induce hemolysis when grown on Blood agar is used to classify certain Microorganisms Jules Jean Baptiste Vincent Bordet ( Soignies ( Belgium) 13 June, 1870 &ndash 6 April, 1961) was a Belgian An opsonin is any molecule that acts as a binding Enhancer for the process of Phagocytosis, for example by coating the negatively-charged molecules on the membrane Antibodies (also known as immunoglobulins, abbreviated Ig) are Gamma globulin Proteins that are found in Blood or other Bodily The complement system is a Biochemical cascade that helps clear Pathogens from an organism It is derived from many small plasma proteins that work together to disrupt the target cell's plasma membrane leading to cytolysis of the cell. Proteins are large Organic compounds made of Amino acids arranged in a linear chain and joined together by Peptide bonds between the Carboxyl The cell membrane (also called the plasma membrane, plasmalemma, or "phospholipid bilayer" is a Selectively permeable Lipid bilayer The complement system consists of more than 35 soluble and cell-bound proteins, 12 of which are directly involved in the complement pathways. ^[2] The complement system is involved in the activities of both innate immunity and acquired immunity.

Activation of this system leads to cytolysis, chemotaxis, opsonization, immune clearance, and inflammation, as well as the marking of pathogens for phagocytosis. Cytolysis, or osmotic lysis, occurs when a cell bursts due to an osmotic imbalance that has caused excess water to move into the cell Chemotaxis, a kind of Taxis, is the phenomenon in which bodily cells bacteria, and other single-cell or Multicellular organisms direct their movements An opsonin is any molecule that acts as a binding Enhancer for the process of Phagocytosis, for example by coating the negatively-charged molecules on the membrane Inflammation ( Latin, inflamatio, to set on fire is the complex biological response of vascular tissues to harmful stimuli such as Pathogens Phagocytosis is the cellular process of engulfing solid particles by the Cell membrane to form an internal Phagosome, or "food vacuole The proteins account for 5% of the serum globulin fraction. Globulin is one of the two types of serum Proteins the other being albumin. Most of these proteins circulate as zymogens, which are inactive until proteolytic cleavage. A zymogen (or proenzyme) is an inactive Enzyme precursor. A zymogen requires a biochemical change (such as a Hydrolysis reaction revealing the A protease is any Enzyme that conducts Proteolysis, that is begins protein Catabolism by Hydrolysis of the Peptide bonds that link

Three biochemical pathways activate the complement system: the classical complement pathway, the alternate complement pathway, and the mannose-binding lectin pathway. The classical pathway of activation of the Complement system is a group of blood proteins that mediate the specific Antibody response The alternative pathway of the Complement system is a humoral component of the Immune system 's natural defense against infections which can operate without antibody The Mannan-binding lectin pathway (also known as the Ali/Krueger Pathway is homologous to the Classical complement pathway. The classical complement pathway typically requires antibodies for activation and is a specific immune response, while the alternate pathway can be activated without the presence of antibodies and is considered a non-specific immune response. ^[2] Antibodies, in particular the IgG1 class, can also "fix" complement.

Antibodies

Main article: Antibody

Immunoglobulins are glycoproteins in the immunoglobulin superfamily that function as antibodies. Antibodies (also known as immunoglobulins, abbreviated Ig) are Gamma globulin Proteins that are found in Blood or other Bodily The terms antibody and immunoglobulin are often used interchangeably. They are found in the blood and tissue fluids, as well as many secretions. In structure, they are large Y-shaped globular proteins. In mammals there are five types of antibody: IgA, IgD, IgE, IgG, and IgM. Each immunoglobulin class differs in its biological properties and has evolved to deal with different antigens. ^[1] Antibodies are synthesized and secreted by plasma cells that are derived from the B cells of the immune system.

An antibody is used by the immune system to identify and neutralize foreign objects like bacteria and viruses. Each antibody recognizes a specific antigen unique to its target. By binding their specific antigens, antibodies can cause agglutination and precipitation of antibody-antigen products, prime for phagocytosis by macrophages and other cells, block viral receptors, and stimulate other immune responses, such as the complement pathway. Agglutination is the clumping of particles The word agglutination comes from the Latin agglutinare, meaning "to glue to

An incompatible blood transfusion, causes a transfusion reaction, which is mediated by the humoral immune response. Blood transfusion is the process of transferring Blood or blood-based products from one person into the Circulatory system of another In Medicine, a transfusion reaction is any Adverse event which occurs because of a Blood transfusion. This type of reaction, called an acute hemolytic reaction, results in the rapid destruction (hemolysis) of the donor red blood cells by host antibodies. Hemolysis (or haemolysis)—from the Greek Hemo-, Greek meaning blood - Lysis, meaning to break open—is the breaking Red blood cells are the most common type of Blood cell and the Vertebrate body's principal means of delivering Oxygen to the body tissues via the Blood The cause is usually a clerical error (i. e. the wrong unit of blood being given to the wrong patient). The symptoms are fever and chills, sometimes with back pain and pink or red urine (hemoglobinuria). Urine is a liquid waste product of the body secreted by the Kidneys by a process of filtration from Blood and Excreted through the Urethra. In Medicine, hemoglobinuria is a condition in which the Oxygen transport Protein Hemoglobin is found in abnormally high concentrations in the The major complication is that hemoglobin released by the destruction of red blood cells can cause acute renal failure. Hemoglobin ( also spelled haemoglobin and abbreviated Hb or Hgb) is the Iron -containing Oxygen -transport Metalloprotein Acute renal failure ( ARF) also known as acute kidney failure or acute kidney injury, is a rapid loss of Renal function due to damage to the

B cells

Main article: B cell

The principal function of B cells is to make antibodies against soluble antigens. B cells are Lymphocytes that play a large role in the humoral immune response (as opposed to the cell-mediated immune response, which is governed by B cell recognition of antigen is not the only element necessary for B cell activation (a combination of clonal proliferation and terminal differentiation into plasma cells). Plasma cells (also called plasma B cells or plasmocytes) are cells of the Immune system that secrete large amounts of antibodies.

Naive B cells can be activated in a T-cell dependent or independent manner, but two signals are always required to initiate activation.

B-cell activation depends on one of three mechanisms: Type 1 T cell-independent (polyclonal) activation, Type 2 T cell-independent activation (in which macrophages present several of the same antigen in a way that causes cross-linking of antibodies on the surface of B cells), and, T cell-dependent activation. During T cell-dependent activation, an antigen presenting cell (APC) presents a processed antigen to a helper T (T_h) cell, priming it. T cells belong to a group of White blood cells known as Lymphocytes, and play a central role in Cell-mediated immunity. See also Antigen presentation An antigen-presenting cell ( APC) or accessory cell is a cell that displays foreign Antigen complexed When a B cell processes and presents the same antigen to the primed T_h cell, the T cell releases cytokines that activate the B cell. Cytokines are a category of signalling Proteins and Glycoproteins that like Hormones and Neurotransmitters, are used extensively in cellular ^[2]

See also

• Immune system
• Immunity
• Polyclonal response

References

Further reading

• The following article reviews some of the early experiments that laid the foundations of the humoral theory:

Meltzer, S. J. and Charles Norris (1897) The Bactericidal Action of Lymph Taken From the Thoracic Duct of the Dog. (Full Text-pdf) Journal of Experimental Medicine Vol. 2, Issue 6, 701-709.

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