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22 Cards in this Set
- Front
- Back
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A gene codes for
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alpha (1,3) N-acetylgalactosaminyltransferase
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B gene codes for
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alpha (1,3) galactosyltransferase
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blood antigens come from
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genes on chromosome 9
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Blood group pheotypes
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A,B, AB, O
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Blood group genotypes
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AA/AO; BB/BO; AB; O
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Bombay antigen
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they don't even have H antigen; missing fucose
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H antigen
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is the normal antigen on RBC and a transferase adds the other things on it
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Isoagglutinins
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serum antibodies; IgM class; appear 2 months of age - response to gut flora (bacteria similar to human red cell antigens); most important in ABO system; agglutinate RBC
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Group A people make these types of antibodies
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anti-B antibodies
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Group B people make these types of antibodies
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anti-A antibodies
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Immune-mediated transfusion rxns
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usually due to ABO incompatibility; donor RBC destroyed by patient antibodies; patient RBC destroyed by donor isoagglutins; donor WBC destroyed by pateint antibodies
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Non-immune mediated transfusion rxns
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bacterial/viral contamination; RBC damage; circulation overload
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Rhesus system
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Cc,Dd(d means no D),Ee; if any big D it is Rhesus positive; no isoagglutinins; found on chromosome 1; RhD gene encodes D antigen; RhCE encodes Cc and Ee antigens
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If someone is Rh+ can they have a Rh - child?
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Yes, they could be hetereozygous;
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Hemolytic disease of newborn
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aka erythroblastosis fetalis, Rhesus disease, hydrops fetalis; results of blood group incompatibility between mother and fetus; most serious disease is caused by Rhesus incompatibility (Rh- mother, Rh+ fetus; ABO incompatibility; preventable* , rare
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how hemolytic happens
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1st baby is Rh+ with Rh- mom; after birth mom and baby's blood exchanges and mom makes antibodies against; when next baby with Rh+ is implanted mom will make IgG anti-D antibodies against and attack across placental barrier; could be sensitized at previous miscarriage
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Which antibodies cross placental barrier
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IgG only! Through active transport - involves IgG Fc receptors on placenta; transfers both beneficial and harmful antibodies
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Kernicterus
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unconjugated bilirubin causes jaundice - can also cross blood-brain barrier in infants (neurotoxin)
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Prevention of Rhesus disease
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RHOGAM - human IgG anti-D; adminstered to every Rh (-) mom after each Rh+ baby; prevents sensitization to D antigen
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Direct Coombs tests
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detect antobodies on erthrocytes; for at risk baby at birth; coombs reagent is rabbit anti-human Ig to see if mom's antobodies are already attacking babies RBC; so positive test means baby has mom's antobodies attached to it
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Indirect Coombs test
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detects anti-erythrocyte antibodies in serum; basically checks to see if pregnant mother hads antibodies to D antigen
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ABO incompatibility protects against Rh incompatibility
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if the baby is a different blood type then IgM isoglutinins attack any blood that may eneter mom; by this happening it prevents mom from making IgG to D which will hurt baby
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