Blood groups dr.sahar jabbar kadhum

When blood transfusions from one person to another were done without matching, immediate or delayed agglutination and hemolysis of the red blood cells often occurred, resulting in typical transfusion reactions that frequently led to death

The ABO blood groups consist of blood types A, B, AB, O, depending on presence or absence of type an antigen. These antigens occur on the surfaces of the red blood cells. also called agglutinogens because they often cause blood cell agglutination,and cause most transfusion reaction.

AntiA+AntiB Agglutinin Blood group AGGLUTINOGEN (ANTIGEN) Type of agglutinin (antibody) Blood group A A Anti B Agglutinin blood group B B Anti A Agglutinin blood group AB A+B ------ blood group O ---- AntiA+AntiB Agglutinin

Genetic Determination of the Agglutinogens. Two genes, one on each of two paired chromosomes, determine the A-B-O blood type. These genes can be any one of three types but only one type on each of the two chromosomes: type O, type A,typeB

Agglutinogens Genotypes BLOOD TYPES Agglutinins 00 O ---- Anti A + Anti B OA or AA A AntiB OB or BB B Anti A AB A +B

Frequency of different blood types Blood group percentage O 47% A 41% B 9% AB 3%

When type A agglutinogen is not present in a person’s red blood cells antibodies known as anti-A agglutinins .develop in the plasma. when type B agglutinogen is not present in the red blood cells, antibodies known as anti-B agglutinins develop in the plasma.

Origin of Agglutinins in the Plasma The agglutinins are gamma globulins, They are produced by bone marrow and lymph gland cells that produce antibodies to any other antigens. most of them are IgM and IgG immunoglobulin molecules.

Small amounts of type A and B antigens enter the body in food, in bacteria, and in other ways. and these substances initiate the development of the anti-A and anti-B agglutinins.

Agglutination Process In Transfusion Reactions When bloods are mismatched so that anti-A or anti-B plasma agglutinins are mixed with red blood cells that contain A or B agglutinogens , respectively.

the red cells agglutinate as a result of the agglutinins’ attaching themselves to the red blood cells. Because the agglutinins have two binding sites(IgG type) or 10 binding sites (IgM type). a single agglutinin can attach to two or more red blood cells at the same time, thereby causing the cells to be bound together by the agglutinin.

This causes the cells to clump, which is the process of “agglutination This causes the cells to clump, which is the process of “agglutination.” Then these clumps plug small blood vessels throughout the circulatory system. During ensuing hours to days, either physical distortion of the cells or attack by phagocytic white blood-cells destroys the membranes of the agglutinated cells , releasing hemoglobin into the plasma, which is called “hemolysis” of the red blood cells.

A person ABO blood type can be determined by placing one drop of blood in a pool of anti A serum and another drop in a pool of anti B Serum. blood type AB will show conspicuous agglutination in both antisera . Type A or B will agglutinate only in the corresponding antiserum and type O will not agglutinate in any one.

in giving transfusion ,it is imperative that the donors blood not agglutinate as it inters the recipients blood stream . for example, if type-B blood were transfused into type A recipient ,the recipients anti B agglutinins would immediately agglutinate the donors RBCs . a mismatched transfusion causes transfusion reaction ,the agglutinated RBCs block small blood vessels. hemolysis and release their Hb over next few hours to day.

free Hb can block the kidney tubules and can cause death within a week or acute renal failure . for this reason ,person with type A (anti-B) blood must never be given a transfusion of type B or AB blood. Type(AB) group, called universal recipient ,while(O group) universal donor.

RH SYSTEM Along with ABO blood group ,the RH System is important in the transfusion of blood . In ABO ,the agglutinin responsible for causing transfusion reaction develop spontaneously, where as in Rh- system spontaneous agglutinins almost never occur agglutinins.

O+ve

there are 6 types of Rh-antigens ,each of which is called Rh- factor ,these types are C ,D ,E ,c , d, e . a person who has C antigen doesn't have c antigens , but person missing the C antigen always has the c antigen. the same for Dd ,and Ee antigens

so 85% of persons have Rh+,15% have Rh- ve. type D widely prevalent in the population therefor ,anyone have this type (D)called RH+. if not have RH type D ,called RH negative. so 85% of persons have Rh+,15% have Rh- ve.

. formation of anti RH ,agglutinins. When RBC containing RH factor or even protein, breakdown products of such cells are injected into a person whose blood does not contain Rh factor(Rh-ve) ,so anti Rh agglutinins develop slowly and maximum concentration of agglutinin occurring about 2-4 months. .

On multiple exposure to Rh factor, The Rh -ve person become strongly sensitized to Rh +ve factor.

Erythroblastosis fetalis hemolytic disease of newborn This disease of fetus characterized by agglutination and phagocytosis of RBC . in most instances of this disease ,the mother is Rh-ve ,the father Rh +ve The fetus inherited Rh +ve from father ,and mother developed anti Rh agglutinins from exposure to baby's Rh antigen ,in turn the mother agglutinins diffuse through the placenta to the fetus and cause RBCs agglutination

Effects of mother antibodies on the fetus The agglutinated RBC s subsequently hemolyze ,releasing Hb into the blood .the macrophages then convert the Hb into bilirubin which causes the skin to yellow (jaundice). the antibodies can also attack and damage other cells of the body. the jaundiced erythroblastosis neonate is usually anemic at birth

and anti Rh agglutinins from mother usually circulate in the infants blood for 1-2 months after birth, destroying more and more RBCs the usual treatment is to replace the neonates blood with Rh -ve blood ,about 400 milliliters of RH–VE blood is infused over a period of 1.5 or more hours while neonates own Rh +ve blood is being removed .the Rh-ve cells are replaced with the the baby own Rh +ve cells.

Transfusion reactions resulting from mismatched blood types The donors blood of blood type is transfused to a recipient of another blood type. Transfusion reaction is likely in which the RBCs of donor blood are agglutinated It is rare that the transfused blood causes agglutination of recipients cells ,the plasma portion of the donors blood immediately become dilated by all plasma of recipient,

There by decreasing the titer of infused agglutinins to a level low to cause agglutination . on other hand ,the infused blood does not dilute the agglutinins in the recipients plasma to major extent . therefore, the recipients agglutinins can still agglutinate the donors cells

Nature of antibodies -The antibodies are Gama globulin called immunoglobulin IgG and molecular weight 160,000-970,000 and constitute 20%of all plasma protein. -Contain light and heavy chain polypeptide chains ,2light and 2 heavy chains. -Antigen bind as two different sites on the variable portion of the chain.

some Ig have combination 10 heavy and 10 light, each antibody is specific for particular antigen ,this caused by the structural organization of amino acids in variable portion of both light and heavy chain. There are many bonding sites between antibody antigen . coupling become strong ,& held together by 1- hydrophobic bonding 2-hydrogen bonding 3-ionic attractions 4-van der waals forces

There are 5 general classes of antibodies ,respectively IgM ,IgG ,IgA ,IgD , and IgE . IgM, the antibodies have 10 binding sites that make them exceedingly effective in protect the body against invaders.

The antibodies acts mainly in two ways to protect the body invading agents by direct attack on the invader and by activation of complement system.

In the direct attack the antibody like Y- shaped bars, reacting with antigens ,because of bi valet nature of the antibodies and multiple antigen sites on most invading agents ,the antibodies can inactivate the invading agents in several ways.

1-agglutination,in which multiple large particles with antigen on their surface like bacteria ,or RBC ,are binding together and form clump. 2-precipitation,in which the molecular complex of soluble antigen(tetanus toxin) and antibody become so large that it is rendered insoluble and precipitates. 3-nutralization in which the antibodies cover the toxic sites of the antigenic agent

4- lysis in which some potent antibodies are capable of directly attacking membranes of cellular agents and there by causing rapture of the cells. The activation of complement Complement is collective term describe a system of about 20 protein ,many of which are enzyme precursors.