TYPE II HYPERSENSITIVITY Flashcards
Examples of type 2 hyper
Hemolytic anemia of newborns
Penicillin induced anemia.
Some autoimmune diseases
Blood transfusion reactions
Type 2 hyper is caused by
Type II: destruction of normal tissue (cells) by antibody (IgG or IgM)
When and why are transfusions performed?
When extreme blood loss is noted and a PCV is below 12
Risk of reaction to a first transfusion?
Species dependent
Many species minimal risk to FIRST transfusion
What may vet techs do for transfusions
Collect blood.
Minimize risk of reaction (blood type and cross match)
Administer the transfusion.
Monitor the transfusion
ACD solution is
Acid Citrate dextrose
This is an anticoagulant and energy source
Human blood collection packs (ready to go)
Sigma Chemical Co
Blood group antigens are
The molecules expressed on the surface of RBC’s are called blood group antigens.
Not involved in antigen processing
Name often starts with a species code and EA (Erythrocyte Antigen)
Followed by letter or number denoting order of discovery.
Transfusion reactions can happen because
Recipient may contain pre-existing antibodies as a result of previous exposure:
To blood- prior transfusions or pregnancies
To similar antigens through diet
Vaccinations – some contain animal tissue.
Dietary risk is species dependent.
Cattle
Mechanism by which blood transfusion reactions occur
Significant clinical signs if infused with large amounts of incompatible blood into a sensitized patient.
Mechanism: pre-existing antibody binds to erythrocyte antigens
Agglutination
Opsonization
Complement activation results in:
Hemolysis
Free hemoglobin can damage the kidneys.
Anaphylatoxin and mast cell degranulation
Prevention of transfusion reactions
Major and minor cross mach
Minor cross match uses
Donor serum and patient RBC
Major cross match is
Most important is donor RBCs with patients serum
Major cross match
Look for:
Lysis
Agglutination
Mild to moderate transfusion reaction
Sweating, salivating, diarrhea, vomiting
Increased RR or HR
Fever
Severe transfusion reaction
Shock
Weakness
Hypertension
Hypotension
Tachycardia
Bradycardia
Tachypnea
Dyspnea
DIC
Collapse
Death (Arrhythmia or apnea)
What to do if a transfusion reaction occurs
STOP the transfusion
ALERT the DVM
Maintain urine production.
IV fluids and diuretics
Medications
Diphenhydramine
+/- Epinephrine
Recovery phase after. a transfusion reactions
Hemoglobin eventually converted to bilirubin.
Icterus of mucosae and sclera
What color is icterus?
Yellow
Blood transfusion in cattle
MANY blood types.
Used to check parentage
Transfusions are usually incompatible.
So many different blood types
Some cattle have performed Ab against foreign RBC antigens.
Antibody seen in cattle that have had no previous blood transfusions.
Due to dietary antigens?
First transfusion last days to a week
Repeated transfusions – shorter life of RBCs
DEA 1 in dogs is
DEA 1 is a strong antigen.
Causes the most significant problems
Several laboratories make a card test to detect this Ag.
DEA 1.1 subgroup is the major concern within DEA 1 dogs.
Blood in dogs
No preformed antibody against foreign antigens
Many RBC antigens
DEA 1.1 is what type of donor
So, DEA 1.1 positive dogs are Universal Recipients
DEA 1.1 negative dogs are Universal Donors
Transfusing a DEA 1.1 negative dog with positive blood leads to:
First transfusion is “free”
Means no antibody present at first transfusion
Transfusion reactions on subsequent transfusions
Potential problems in puppies if pregnant (neonatal isoerythrolysis)
Recommended that always cross match on subsequent transfusions and in breeding bitches
Problems on first transfusion prevented by testing for strong antigens
yes
On subsequent transfusions prevented by testing for strong antigens
Yes
Small risk of incompatibilities form minor antigens
Does cross matching first transfusion prevent problems on the first transfusion
Yes
Does cross matching first transfusion prevent problems on subsequent transfusions
No
Maybe incompatible on second transfusion even though compatible first
Transfusions in horses
Many blood groups but only 2 are important.
No preformed antibody
Unless previously exposed to antigenic RBCs
Sensitization through vaccination?
Risk of reactions for blood transfusions in horses
Like dogs
Except multiparous pregnant mares have a higher risk
Three blood types for cats
A, B and AB
99% of DSH and DLH cats in North America are type A
Type B is more prevalent in some Pure Breeds
Type AB is rare - <1-6%
Siamese and Burmese
All type A
Exotics, British Shorthair, Cornish Rex and Devon Rex
Up to 60% Type B
UK cats, 40% are Type A, 60% Type B
What antibodies do type B cats posses
Most type B cats posses IgM against Type A antigens
Even though no previous transfusions
Why?
Alloantibodies
Transfusions in cats
RBC half-life of 4-5 weeks with a donor and recipient match
If Type B blood is transfused into a Type A cat, RBC half-life is only a few days.
Type A blood to a Type B cat, RBC half-life of 1 hr
Low risk for north American domestic cats
Neonatal Isoerythrolysis is
Also called hemolytic disease of newborn
Result of ingesting colostrum with antibody against neonate’s RBCs
Only a common problem in horses and mules
Occasional problem in cats, dogs, pigs, and sheep
Rare in cattle
Neonatal Isoerythrolysis occurs when in horses
Stallion has different blood group (antigens) than mare - foal inherits some of these antigens.
Aa, Qa antigens cause most problems -90% of cases
Dam is sensitised
Leakage of foal blood due to placental bleeding or at parturition
Another possible cause?
Previous transfusion
Foal must ingest colostrum
Who is most likley to get Neonatal Isoerythrolysis
Especially thoroughbred and standardbred mares that have had several foals
0.05-2% of foals affected
Mules
Mules are
What is a mule?
An interspecies cross (Donkey stallion X Mare)
Large genetic differences
8-10% of foals affected with Neonatal Isoerythrolysis
Signs of Neonatal Isoerythrolysis
The signs of hemolytic anemia
Mucous membranes
Pale (initial)
Icteric later
Possibly hemoglobinuria - diagnostic
Weakness, lethargy, possibly shock and death.
Treatment of Neonatal Isoerythrolysis
Prevent or stop colostrum ingestion.
For at least 36h
Ideally, feed colostrum from another mare.
Alternative?
Can give serum from an unrelated horse
Oxygen, fluid and electrolytes, antimicrobials
Blood transfusion if PCV <15%
Convenient source is washed RBCs from dam
Can perform by letting RBC settle by gravity.
Tests for Neonatal Isoerythrolysis
PCV Mild
-Hct = 0.15 to 0.24 L/L or PCV = 15-25%
PCV Severe <15%
Jaundiced Foal Agglutination Test
Mares’ colostrum is combined with foal’s RBCs.
Positive agglutination test
Test mares blood during pregnancy for rising titers of antibodies against Aa or Qa antigens
Neonatal Isoerythrolysis in cats is Cats
One of the causes of “fading kitten syndrome”
Rare in north america
More common in the UK
Most likely to be seen when a blood Type B queen is mated with a blood Type A Tom
Neonatal Isoerythrolysis in Cats is caused by what queen and tom blood types
Blood Type B Queen x Blood Type A Tom
Type A is dominant.
Queen will be genotype bb
Tom will be genotype aa or ab
So, offspring will be:
If Tom aa
All kittens will be ab (type A)
If Tom ab
Kittens will be ab (type A) or bb (type B)
What cats would get Neonatal Isoerythrolysis
Blood group A offspring at risk of neonatal isoerythrolysis from anti-A antibody in the colostrum
Chance of disease is small if blood Type A Queen and Type B Tom
Blood type A cats have less preformed anti-B antibody
Clinical signs of Neonatal Isoerythrolysis
Anemia, icterus, weakness, hemoglobinuria
Type II drug hypersensitivities
Drug or its breakdown products bind to cells making them appear foreign (antigenic)
Example penicillin associated hemolytic anemia.
Rare, seen occasionally in horses.
Vaccines grown on tissue.
Cattle killed BVD vaccine grown on kidney cells
Contained potent adjuvant.
Stimulated anti-MHC Ab production.
Transferred to calves in colostrum and caused pancytopenia
In which species is a first blood transfusion likely to be successful even if there is no cross matching?
Dogs, horses
Define Type II hypersensitivity.
IgG/IgM antibody attacking normal tissue
Why might a 1-day old foal be severely anemic?
Neonatal isoerythrolysis
ACD solution has the following formula:
Trisodium citrate 22.0g
Citric acid (monohydrate) 8.0g
Dextrose (monohydrate) 24.6g
Distilled water to make up to IL
For each 100 ml of blood, need 15 ml of the ACD solution (pH 5.0)
Jaundiced Foal Agglutination Test is
Mares colostrum is combined with foals RBCs
Positive agglutination test when neonatal isoerythrolysis
