Term
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Definition
| Antigens that differ among members of the same species. Blood antigens are allo antigens. |
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Term
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Definition
| Blood antigens are alloantigens that are proteins/sugars whose structure is determined by the presence of genes coding for glycosyl transferases with a diverse chemical composition, divere method of inheritance, and diverse mechanisms of expression. |
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Term
| What is the most important blood group system? |
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Definition
| ABO, but it is not the only one |
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Term
| What antigen in the ABO blood group is found in all people? What is the exception though? |
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Definition
| The H antigen, but it is missing in a certain form of leukocyte deficiency and these people are deemed as having the Bombay blood group phenotype. |
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Term
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Definition
| The H antigen is found and expressed in all people, including Type O people and it acts as the ABO blood group system backbone in that any blood antigens made by an individual are placed on the last 3 sugars of the H antigen stem. The H antigen stem encodes for a fucosyl transferase (basis of the O blood type) |
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Term
| Explain the Bombay Blood Group Type |
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Definition
| The Bombay blood group type has no H antigen present which codes for a fucosyl transferase, in fact these people actually develop natural antibodies toward the H antigen. They are normally deemed type O for the sake of simplicity since they don't have any blood antigens on their RBC surfaces like normal type O people, but keep in mind that they are NOT the same thing. |
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Term
| What sugar does type A individuals express? |
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Definition
| The A allele for type A blood people encodes an N-acetylgalactosamine glycosyl transferase. Type A antigen is a galactose amine sugar. |
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Term
| What sugar does type B individuals express? |
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Definition
| The B allele for type B blood people encodes a galactosyltransferase so type B is just a galactose sugar. |
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Term
| Is the carb structure of ABO recoginized by T cells? |
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Definition
| No. It is only recognized by specific B cells. This makes sense because recall that T cells can only recognize protein antigens that are linear and bound to MHC but B cells can recognize any sort of antigen whether it is free or bound to MHC. So keep in mind that isohemagglutinin immune responses (immune responses to different blood type antigens) are T independent. |
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Term
| Are isohemagglutinin immune responses T dependent or T independent? |
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Definition
| They are T independent because the only thing that differentiates one blood type from another is the type of sugar/carb antigen that is present on the surface of the RBC. Tcells cannot recognize sugars, they can only recognize linear peptides. |
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Term
| Where are blood group antigens intitially thought to develop from? |
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Definition
| They ae intially thought to develop from normal gut bacterial flora because they share epitope structures with similar carbohydrates found on normal gut bacterial flora. This is where they come from during the time the fetus is in utero and until it is atleast 3 months of age. |
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Term
| When do we start to create natural antibodies towards blood types that aren't our own? |
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Definition
| We start to create natural antibodies known as isohemagglutinin after the first 3 months of life after birth. At birth, there are no fetal antibodies against the ABO system because the mother's antibodies are never passed on to her child since blood antigen antibodies are usuall IgM and IgM cannot cross the placenta. |
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Term
| What are natural antibodies called? |
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Definition
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Term
| Type A people have what antigen on their RBCs? What genotype can they be? And what antibodies do they make? |
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Definition
| Type A people have A type anting on their RBCs can be genotype AA or AO and they make Anti-B antibodies to fight off type B blood |
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Term
| What antigen to type B people express? What is their genotype? And what antibodies do they produce? |
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Definition
| Type B people have B antigen on their RBCs can be genotype BB or BO and they make Anti-A antibodies to fight off type A blood |
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Term
| Type AB people have what antigens on their RBC surface? What antibodies do they make? And what genotype are they? |
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Definition
| Type AB people have A and B antigens on their RBCs are genotype AB. They don't make any antibodies toward blood antigens which means they are a universal recipient because thye won't fight off any type of blood they receive. |
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Term
| Type O people have what antigens on their RBC surface? What genotype are they? And what antibodies do they produce? |
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Definition
| Type O people don't have either A nor B antigens on their surfaces. They are genotype OO and they make both Anti-A and Anti-B antibodies. They are the universal donors because no one fights off this type of blood since it has not antigens to fight off. |
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Term
| What blood type is Codominant? |
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Definition
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Term
| What alleles in the ABO system are recessive? |
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Definition
| The H allele and O phenotype are recessive. |
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Term
| What happens in blood typing? |
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Definition
| When testing someone's blood to see what blood type they are, remember that if there is agglutination in the sample, then one of the antibodies you added to the blood had bound to its corresponding antigen in the blood so the person is that blood type. |
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Term
| What is the second most common blood group? |
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Definition
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Term
| What Rh antigen is the only one we care about? Why? |
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Definition
| Type D or d (also called Rho) is by far the most common of the Rh blood antigen system. It is the most highly immunogenic and clinically the most important |
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Term
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Definition
| Rh+ means that the Rho factor D is present on RBCs and Rh- means that it is not present |
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Term
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Definition
| No because d blood has no antigens on it so it poses no threat. However, d poeple have a problem with D blood because it contains an antigen they don trecognize so they try to fight it off. |
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Term
| What could be a trick question for Rh+ blood? |
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Definition
| Rh+ people can NEVER make antibodies toward Rh- blood because d is not an antigen so there is no point in making antibodies for it. |
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Term
| What type of immunoglobulin are Rh molecules? |
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Definition
| Rh antigens are IgG antibodies so they can cross the placenta and can therfore pose a threat to a fetus unlike the ABO blood group system which are IgM |
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Term
| What type of immunoglobulins are the ABO blood antibodies? |
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Definition
| The ABO antibodies are IgM so they can't cross the placenta and pose a threat to a fetus unlike Rh antigens which are IgG |
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Term
| What is a proposed problem for Rh- mothers with Rh+ fetuses that have been exposed to the Rh+ antigen from other sources? |
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Definition
| The mother can already have induced antibodies following a mis-matched transfusion, pregnancy or an abortion which means she has already been sensitized to the Rh+ before. |
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Term
| What is a cause of a transfusion reaction? What is the most serious transfusion reaction? |
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Definition
| Transfusion reaction occur because of reactivity between recipient antibodies and transfused RBCs. The most serious transfusion reaction occurs when two individuals are Rh incompatible and ABO incompatible |
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Term
| What are the symptoms associated with transfusion reactions? |
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Definition
| Severe hemolytic reactions occur within minutes as well as diffuse muscular pain, headache, vomiting, a rise in temperature, shock and renal failure. |
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Term
| What is hemolytic disease of the newborn? |
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Definition
| Occurs in Rh- mothers that have an Rh+ baby. The second most common HDN blood group is kell. HDN can happen after a 2nd pregnancy with an Rh+ baby (if the first child was also Rh+). HDN can happen to the first Rh+ baby a woman has if the mother had previously received a mis-matched transfusion or if the mother had previously received a mis matched transfusion or if the mother had a previous miscarriage or abortion of an Rh+ baby. In the case of HDN, the Rh+ allele (the D allele) of the fetus HAS to come from the father (obviously). The way HDN usually occurs is that the mother becomes sensitized with her first baby's cells when they enter the circulation during her first pregnancy (this number is usually too low to induce any problems for that first baby) during delivery. Specifically, during delivery, upon placenta separation, the mother is exposed to massive Rh+ RBCs from the cord blood of the baby. The mother becomes immunized, producing anti Rh+ IgG, which can then cross the placenta of a subsequent Rh+ fetus and damage it. |
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Term
| When is there a reduced risk for HDN? What happens? |
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Definition
| For some reson, ther is a reduced risk of HDN if there is a blood type incompatibility with the fetal red cell antigen. Normally ocurring anti-A and anti-B blood group antibodies in the mother may clear antigenic Rh+ fetal RBCs and prevent sensitization, but this only occurs if the baby expresses the appropriate blood group. |
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Term
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Definition
| Rhogam (a combination of anti-Rh+ IgG) can be administered to a mother after the delivery of her first Rh+ child (within the first 24-72 hours after birth). This will rid any Rh+ cells rapidly, thereby preventing the formation of anti-Rh positive IgG in the mother that would then stick around forever in her system. There is also evidence that Rhogam interacts with the Fc receptors on Anti-Rh specific B cells and downregulates their responsiveness as well as the development of class switched memory cells. |
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Term
| What is blood typing used for? |
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Definition
| blood typing is used to determine agglutination using commercial antibodies against A, B and D antigens |
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Term
| What is Cross Matching? What are the tests call that are done? |
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Definition
| Between a donor and a recipient, this method detects antibodies against blood group antigens and provides a more reliable measure. The Coombs test is done. |
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Term
| What is the direct Coombs test? |
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Definition
| The direct Cooms test detects that presence of antibodies on RBCs. For example, if you want to test a baby to see if it has antibodies from its mother on its RBCs attacking them you use this test. So you use this to test a baby with HDN to scertain the presence of Rh positive antibodies on its RBC surfaces. This is actually done by adding an antibody that recognizes the human antibodies already attached to the abby's RBCs and this second antibody that we add is called anti-human IgG it's known as the Cooms reagent. The Coombs regent will agglutinate a patients RBCs if they are sensitized with another antibody. The mother would give a negative Direct Coombs' test because her RBCs aren't being attacked, so how do we test the mother to see if she has antibodies towards her baby's RBCs? We used the Indirect Coombs's test! |
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Term
| What is Indirect Coombs' Testing? |
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Definition
| Detects the presence of antibodies AGAINST RBC antigens. To test the mother of an HDN baby to see if she has antibodies towards his RBC antigens we add antibodies into her serum that will agglutinate if they find antibodies towards the baby's RBCs. The antibodies that we add to her blood we abtain from a commercial source. |
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