Complex antigen-antibody

A complex immune (or complex antigen-antibody ) results from the combination of a épitope with a Anticorps directed against this épitope. After this reaction, usually physiological, the complex can be introduced by Phagocyte S or transformed by Protéase S.

However, the complexes immunes can cause diseases by themselves, when they settle in bodies, EP in certain forms of Vascularite -- this is the form of Hypersensibilité of the type III in the classification of Freezing and Coombs.

Introduction

A complex immune (or complex antigen-antibody) results from the combination of a épitope (antigen) with an antibody directed against this épitope and only against this antigen. This unit is likely to be inside the serum (left liquid blood) in soluble form or form precipitated inside fabrics.

Physiology

What is what an Antibody?

An antibody is a protein contained in blood (more precisely in the blood serum) than one also calls immunoglobulin (abbreviation: Ig). The molecule of antibody is composed of 4 polypeptides: 2 heavy chains (H, Heavy) identical of 50 kda and 2 light chains (L, Light) identical of 25 kda chacunes. The light chain is made up of 2 fields, a variable field V and a field C folded up independently one of the other in space. It is synthesized by the cells of the lymphoid apparatus to answer the introduction of a foreign substance: antigen.

What is what an Antigen?

An antigen is a foreign substance of organic nature (coming from alive) having the aptitude to induce, at the time of its introduction into the organization, the formation of specific antibodies. An antigen can return in our organization by the multiple ones carries entered that one him offers which are: respiratory tract, digestive tract, secretions, skin, blood. There exist four different types of antigen: Bacteria, Viruses, Parasites and the Mushroom Yeasts.

Formation & Function of the Complex Immune

Formation:

The complex immune is thus the association of an antigen and an antibody, two things diametrically opposite and yet perfectly assembled by the means of the complex essential immune for the defense of our organization. This association be done thanks to capacity of accommodates antibody for the antigen, of share its structure the antibody has proteinic chains light which are specific of an antigen. The formation of the complex immune proceeds in the following way. First of all one needs an intrusion of an infectious agent for interior of our organization. This is detected by our organization which sends a signal to the cells responsible for the immune system which are the Lymphocytes and in particular in this case there the Lymphocytes B. The latter have the role to produce antibodies of all the kind that he knows i.e. specific has full of antigen different. The different antibody will be trotted in the organization with the research of the person in charge of the infection and there when good the antibody will meet the antigen it will be able' to have formation of the complex immune. The antibody approaches the infectious agent which is specific for him it will be fixed using these light chains on the membrane receivers of the antigen. Once this fixing that have it could compare with the recognition enzyme substrate is carried out the complex immune is formed and ready with employs.

Function:

The complex immune is one of the mechanisms of defense of the immune system. It is qualified mechanism innate it belongs to the primary immunizing response. Indeed during an infection or of an attack of a sudden foreign body by our organization there is initially a primary immunizing response which one describes as innate. This first barrier is ensured by Monocyte and Phagocyte the polynuclear ones. The Complex Immune when has facilitates it these mechanisms by its specificity with only one antigen. Once the antigen was recognized by its antibody thanks to its light chains specific it' will start there moving of the complex immune i.e. that association antibody antigen will be fixed has an immunoglobulin. This complex immune will have then the capacity to digest the couple antibody antigen and to eliminate it. This process is called phagocytosis it is carried out in four great stages:

the phase of attraction: it is the moment when once formed the complex immune goes close to the cells phagocytic (monocyte, phagocyte, polynuclear) by chemotactism.
the phase of adherence of the complex immune: the heavy chains nonspecific of the antibody is fixed on a receiver of the membrane of immunoglobulin.

Beginning of intracellular digestion: after the complex immune is to fix on the phagocytic cell there is formation of a digestive vacuole around the complex immune and the lysosome present in immunoglobulin which contain digestive enzymes amalgamate around the complex immune against the vacuole. There is thus release of the digestive enzymes and the complex immune bathes in the enzymes.

Fine of intracellular digestion: when the enzymes finished digesting the antigen there is waste disposal to external of the cytoplasms it is the éxocytose. However it remains of remainder of antigen lyses to interior of immunoglobulin.

IT should be known that when this mechanism does not manage to eliminate totality from the infectious agents it there with the second barrier which is started that one qualifies the specific one. The latter is longer the innate answer. It is carried out by the Lymphocytes B the cytotoxic Lymphocytes T and Lymphocytes T.

Physiopathology

Some disfonctionnement of the complex immune:

The complexes immunes can cause diseases by themselves, in particular the complexes immunes which one describes as circulating. Naturally one notes the appearance of complexes circulating immunes due to immune reactions. It is only the amplification of this normal phenomenon which leads to certain pathologies. Indeed, physiologically the complexes circulating immunes intercept the complements which correspond to varieties of enzymes which take part in the immunizing mechanisms of the organization against the antigens. As of this moment the complex antigen antibody i.e. the aggregation of both, after having circulated inside blood, is eliminated thanks to the intervention from the components contained in the lymphoid bodies (system réticulohistiocytaire) i.e. the cells having the capacity to eliminate waste in blood. However actually the phenomenon is a little different and the complex immune can be found in three situation different i.e. to evolve/move in a different way in the organization what can have consequences variable.

Here three possible cases:

Is the antigen and the antibody is neutralized respectively in this case there all occurs that normally thus does not involve any complication.

Is the antibody is in excess and in this case one notes the formation of insoluble complexes which will be quickly destroyed by the organization.

This destruction is done either by precipitation (solidification and neutralization) or by phagocytosis (absorption then digestion by a particulate variety of white globules, the phagocyte.

Is the antigen is in excess and in this case the complexes are soluble in the blood serum and remain in circulation. They are then likely to cause morbid phenomena (at the origin of disease). These affections can be “minor” when the antigen has a weak weight (molecular) due to the fact that the complexes settle in a parcelled out way tardily likely then to be destroyed by the red globules thanks to phagocytosis. In certain cases the antigen has a weight (molecular) important associated a big size. In these circumstances one notes a fast precipitation (deposit) and a setting in fast swing of the action of the complement what involves deteriorations of the small vessels and more precisely of their walls relating to certain bodies like the kidneys. This type of phenomenon constitutes the over-sensitiveness of the type III or semi late. Among certain patients one notes racings of this phenomenon what leads to lesions of other bodies such as the skin and the arteries. It is what one notes during the allergic angéite or of the disease with precipitins. The complement is a factor which intervenes in cascade to activate an immune reaction.

List nonexhaustive pathology related to disfonctionnement of the complex immune:

acute Glomérulonéphrite
chronic Glomérulonéphrite
acute érythémateux Lupus disseminated
Syndrome of Gougerot
Sclérodermie
Polyarthrite rhumatoïde
primitive biliary Cirrhose
chronic Hépatite activates
pulmonary Fibrose
Polychondrite atrophying chronic
thrombopenic Maladie of the serum
Poumon eosinophilic
Purpura
interstitial Maladie diffuses
Phénomène of Arthus
Syndromes of Dressler

It should be known that the complexes immunes can also be related to an autoimmune process i.e. the induced patient of the immune reactions against its own fabrics. Treatments: The autoimmune diseases related to the appearance of complexes circulating immunes call above all upon the plasmaphérèse i.e. with plasmatic purification.

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