Alloimmunity
Encyclopedia
Alloimmunity is a condition in which the body gains immunity
against antigens of another individual of the same species, which are perceived as foreign.
Alloimmunity should not be confused with autoimmunity
in which the body's immune system attacks its own cells without being provoked or influenced by substances or cells from another member of the same species.
One alloantigen is known as "Qa-1".
If either alloimmunity or autoimmunity is directed against red blood cells (RBCs), the direct Coombs test
is positive.
that is a part of an animal's self-recognition system. e.g., Major histocompatibility complex molecules. When injected into another animal, they trigger an immune response aimed at eliminating them. Therefore, it can be thought of as an antigen that is present in some members of the same species, but is not common to all members of that species. If an alloantigen is presented to a member of the same species that does not have the alloantigen, it will be recognized as foreign. They are the products of polymorphic genes.
Alloimmunity can be regulated by neonatal B cells.
Immune system
An immune system is a system of biological structures and processes within an organism that protects against disease by identifying and killing pathogens and tumor cells. It detects a wide variety of agents, from viruses to parasitic worms, and needs to distinguish them from the organism's own...
against antigens of another individual of the same species, which are perceived as foreign.
Alloimmunity should not be confused with autoimmunity
Autoimmunity
Autoimmunity is the failure of an organism to recognize its own constituent parts as self, which allows an immune response against its own cells and tissues. Any disease that results from such an aberrant immune response is termed an autoimmune disease...
in which the body's immune system attacks its own cells without being provoked or influenced by substances or cells from another member of the same species.
One alloantigen is known as "Qa-1".
If either alloimmunity or autoimmunity is directed against red blood cells (RBCs), the direct Coombs test
Coombs test
Coombs test refers to two clinical blood tests used in immunohematology and immunology...
is positive.
Pathophysiology
An alloantigen is an antigenAntigen
An antigen is a foreign molecule that, when introduced into the body, triggers the production of an antibody by the immune system. The immune system will then kill or neutralize the antigen that is recognized as a foreign and potentially harmful invader. These invaders can be molecules such as...
that is a part of an animal's self-recognition system. e.g., Major histocompatibility complex molecules. When injected into another animal, they trigger an immune response aimed at eliminating them. Therefore, it can be thought of as an antigen that is present in some members of the same species, but is not common to all members of that species. If an alloantigen is presented to a member of the same species that does not have the alloantigen, it will be recognized as foreign. They are the products of polymorphic genes.
Causes
Alloimmunity can occur- in the recipient after transfusions of fluids such as bloodBloodBlood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells....
or plasmaBlood plasmaBlood plasma is the straw-colored liquid component of blood in which the blood cells in whole blood are normally suspended. It makes up about 55% of the total blood volume. It is the intravascular fluid part of extracellular fluid...
. - in the recipient after allografts (graftsMedical graftingGrafting refers to a surgical procedure to move tissue from one site to another on the body, or from another person, without bringing its own blood supply with it. Instead, a new blood supply grows in after it is placed. A similar technique where tissue is transferred with the blood supply intact...
). - in the fetusFetusA fetus is a developing mammal or other viviparous vertebrate after the embryonic stage and before birth.In humans, the fetal stage of prenatal development starts at the beginning of the 11th week in gestational age, which is the 9th week after fertilization.-Etymology and spelling variations:The...
after maternal antibodies have passed through the placenta into the fetus, as in haemolytic disease of the newborn and fetomaternal alloimmune thrombocytopenia.
Alloimmunity can be regulated by neonatal B cells.