Blood Typing Flashcards
(15 cards)
1
Q
Agglutinogens, agglutinins, hemolysis
A
- Agglutinogens – molecules that can promote agglutination
- Agglutination = clumping of red cells: Important because it is the pathophysiology of transfusion reactions and blood type mismatches, Molecules on the RBC surface and act as antigens in that they can initiate an immune response
- Agglutinins – the actual antibodies that are developed to target the agglutinogens that are produced when exposed to agglutinogens
- Hemolysis – breakdown on blood cells that can happen as a result of a blood mismatch such as in a transfusion
2
Q
OAB
A
- Numerous commonly occurring antigens
- A and B are NOT the only proteins on the surface of a RBC
- OAB and Rh most likely to cause transfusion reactions
- O and A most common
- Type determined by alleles inherited from parents
- A and B exhibit co-dominance, O is recessive (O represents absence of A or B proteins on the RBC)
3
Q
frequencies + and -
A
+ and - refers to the rhesus factor
4
Q
agglutinins
A
- Antibodies to blood surface proteins absent in host
- Host contains antibodies (due to exposures) to other markers
- Agglutinin titers spike around 10 years
- You can give type O more comfortably to type A or B because they don’t have the immune aspects that will cause an adverse reaction
5
Q
the ABO blood system
A
- Type AB blood is the universal recipient
- Type O blood is the universal donor
6
Q
agglutination
A
- Clumping of cells – binding together because of the presence of antibodies on the surface
- Hemolysis of red cells ensues
- Hemoglobin is dumped from lysed erythrocytes
- Hemolysis immediate by complement activation or delayed – it can happen later, not as soon as you administer an incorrect blood type
7
Q
Rh
A
- Named for Rhesus monkey in which it was discovered
- Agglutinin formation slower than for OAB, requires large exposure to get the same kind of response (Can augment the immune response to an A or B mismatch)
- Six proteins: C, c, D, d, E, e (dominant and recessive form for agglutinogens c, d, and e)
- D is most prevalent and most antigenic and, therefore used to confer “positivity” or “negativity” (The others are negative, The person that is Rh – has one of the other 5 alleles)
8
Q
immune response
A
- Rh+ cells to Rh- recipient (Anti-Rh agglutinins develop over months)
- Sensitization occurs with repeat exposure
- On first exposure, delayed reaction at 2-4 wks (mild) (Reaction enhanced for later exposures because now they have the antibodies floating around, This is why we monitor women who get pregnant for their Rh type)
- They will not react to the baby’s difference in Rh, but if the mom gets pregnant again, that baby is at risk for mom’s Rh response
9
Q
erythroblastosis fetalis
A
- what you see is reticulocytes
- Agglutination and phagocytosis of newborn’s RBCs from the mom’s antibodies to the rhesus factors
- Most often baby is Rh+, mother is –
- Mother develops antibodies on exposure to fetal products
- Diffusion of ab through placenta leads to agglutination
- 3% dx in second Rh+ baby, 10% in 3rd because she is being hypersensitized by the repeated exposures
10
Q
fetal response
A
- Agglutination and hemolysis of RBCs
- Hemoglobin released jaundice (Broken down into hemosiderin so they have a hemolytic jaundice)
- Anemia at birth
- Hepatosplenomegaly – spleen is working over time breaking down RBCs and an immune response is happening
- High erythroblast count on blood
- Death via anemia or mental/motor impairment by kernicterus (The buildup of the bilirubin that they cant get rid of is called kernicterus)
- Tx usually by exchange with Rh- cells
11
Q
normal transfusion reactions
A
- Donor red cells agglutinated – less diluted
- If the blood is mismatched, the donor blood will not only have agglutinins, but also agglutinogens to the recipients cell surface that will cause the transfusion reaction
- Hemolysis immediate or delayed
- Jaundice possible
- Severe renal effects
12
Q
transplant
A
- Antigens on red cells common throughout body – we can have immune reactions to transplant tissue – reaction to the transplant of blood
- Types of transplant (Autograft = one part of the same animal to another part of the same animal, From identical twin to identical twin = isograft – represents lower level of risk than other transplants, Allograft = one human to another, Xenograft = any other species to a human)
- Tissue typing
- Immune suppression (We treat with steroids to suppress the recipients immune response permanently or an extended period of time to try to make sure that the recipient doesn’t reject the transplanted tissue or organ)
13
Q
Coomb’s testing
A
- Two tests
- Detect presence of IgG antibodies to RBC surface proteins using anti-human globulin antibodies (Coomb’s reagent). (Reacts to antibodies (an antibody to antibodies), Can do this to RBCs to look for antibodies bound to RBCs (direct) or to plasma (indirect))
- IgG is detected bound to RBC (Direct) or in plasma (Indirect)
14
Q
laboratory testing
A
-Coomb’s Testing
Indirect (for compatibility): Pt serum + test RBCs, wash and add Coomb’s reagent, agglutination demonstrates ab to RBCs in serum (maternal compatibility/screen recipients and donors), We do this to determine maternal compatibilitiy and donor/recipient)
-Direct (for transfusion reaction): Pt RBCs + Coomb’s reagent directly, agglutination demonstrated reaction by host (transfusion rxn), You don’t apply serum or anything else
15
Q
to screen or to cross?
A
- Typing blood = indirect coombs test
- “Type and Screen”: Type blood, conduct indirect Coomb’s test with sample red cells
- “Type and Cross”: Direct Coomb’s test with DONOR red cells to assess reactivity to actual transfusion.
- **Never order fewer than 2 units of blood because of the work involved and you don’t want to have to wait again to have to have them retest
