Hypersensitivity 2 Flashcards
Define a hypersensitivity type 2 reaction
Destruction of normal tissue/cells by antibody (IgG or IgM)) with activation of complement or antibody dependent cell cytotoxicity (using NK cells)
Common examples of type 2 hypersensitivity reactions
Blood transfusion reactions
Hemolytic anemia of newborns
Penicillin induced anemia
Some autoimmune diseases
Why are red blood cells commonly affected in type 2 hypersensitivity reactions?
They do not display MHC
Transfusions are performed with
Blood loss
Trauma
Surgery
Low RBC count
How high is the risk of a reaction to a blood transfusion
Species dependent because some species are able to receive one “free” transfusion without a risk of reaction (body has no antibodies/it was never sensitized to another blood type)
What is ACD (acid citrate Dextrose) solution used for?
Blood collection as an anticoagulant and energy source for RBCs
Often in human blood collection packs
What is the formula for ACD solution?
Trisodium citrate 22.0g
Citric acid (monohydrate) 8.0g
Dextrose (monohydrate) 24.6g
Distilled water to make up to 1L
For each 100ml of blood collected, you need _____ ml of ACD solution (pH 5.0)
15ml
Blood group antigens: name often starts with a species code and EA (erythrocyte antigen) followed by a letter or number denoting the order of discovering, what is DEA 1.1
DEA: dog erythrocyte antigen 1.1: first allele of antigen 1
A recipient of a blood transfusion may contain pre existing antibody as a result of?
Previous blood exposure or exposure through the diet
The risk of dietary exposure to a blood group antibody is species dependent
Who is it often seen in and why?
Cattle and some cats
Due to ingesting colostrum with antibodies
What is the mechanism behind a blood transfusion reaction
Pre-existing antibody binds to the erythrocyte antigens and activates a complement reaction causing:
Hemolysis
Anaphylatoxin release and mast cell degranulation
Free hemoglobin (can cause secondary damage to the kidneys)
How are transfusion reactions prevented
Cross matching
Describe major cross matching
Using the donor’s RBCs and the recipients serum
Look for lysis (complement) and agglutination
Minor cross matching
Donor serum and recipient RBCs
Signs of a mild to moderate transfusion reaction
Sweating, salivation, diarrhea, vomiting, increased RR/HR
What are the signs of a severe transfusion reaction?
Shock Weakness Hyperpnea Hypotension Collapse Death (arrhythmia or apnea)
What are the signs of the recovery phase of transfusion reactions?
Hemoglobin from ruptured RBCs eventfully converted to bilirubin
Icterus (yellowing) of mucosae and sclera