transfusion medicine

Immunology

• Genes code for proteins that live on the surface of every cell

• These are known as cell surface antigens (Ag)

• Antigens define what is ‘self’ and what is ‘foreign’

• Foreign antigens stimulate an immune response

Antigens

• WBCs stick to Ag that are foreign to the body

• They stick to viruses, bacteria, fungi, cancer cells

• They take the foreign Ag to local lymph node

  • Present Ag to T cells

T cells

• Helper T cells

  • Tell B cells to make antibodies (Ab) against that Ag

    • Activated B cell      →         plasma cell that makes Ab

AB

• proteins released into blood stream that stick to that specific foreign Ag everywhere

• These Abs are made from 4 to 14 days after that Ag shows up

• Triggers events that destroy those cells

Memory T cells

• Become active when that Ag shows up again

Memory B cells

• Make the same Ag-specific Ab when that Ag shows up again

Red cell surface Ag

• Like all cells in the body, red blood cells have surface antigens

• The Ag on the red cell is genetically determined

  • Different species have different genes

  • Different individuals within that species have different alleles for those genes

• Different animals within a species can have different red cell surface antigens

• Basis for Blood Groups

Feline AB Blood Groups

• Three possible alleles making three possible red cell surface Ags:

  • A, B, AB

• Inherited via Mendelian law on autosomes

  • Allele A is dominant over b and ab

    • Type A cats can be A/A or A/b or A/ab

    • Type B cats are b/b

    • Type AB cats can be ab/ab or ab/b

  • Which blood type in cats do you think is more common?

    • Type A

Blood type and breeds

• To date no Siamese cat has been documented as type B

• Angora cats reported prevalence for type B is 46.4%

• Type AB

  • Incredibly rare in the U.S.: 0.14%

  • Israel 14.5%

  • Japan 9.7%

  • Ragdolls are more commonly type AB

    • In Italy frequency ranges from 18-24%

• The number of the feline blood types is related to breed and geography

Feline AB blood system

• Have naturally occurring antibodies against the other antigen

• No universal donor in cats

  • Type A cats have weak anti-B antibodies

    • If Type A cat receives Type B blood, the Type B red cells are destroyed (hemolyzed) over 2-3 days, and the type A cat only gets mildly ill

  • Type B cats have strong anti-A antibodies

    • If Type B cat receives Type A blood, the Type A red cells are rapidly hemolyzed—acute hemolytic transfusion reaction—deadly

Blood banks

• Packed red blood cells

  • pRBCs

• Plasma

  • Fresh Frozen (FFP)

  • Frozen (FP)

  • Cryoprecipitate (vWf)

• Whole blood

  • Transfused fresh from in-house donor

• Antibodies are found in plasma or serum

Mik feline red blood cell antigen

• Found in a group of domestic cats in 2007

• Seeing hemolytic transfusion reactions between cats that were blood typed

• Raised the question of other rbc antigens outside the AB system

Feline erythrocyte antigens (FEA)

• Five new blood types 2020

  • FEA 1, 2, 3, 4, 5

  • 1 and 5 most prevalent

  • Some FEA-1 negative cats had NOAb

  • Less FEA-1 positive cats had NOAb

• Mik and FEA explain incompatible transfusions when cats were only blood typed

• Up to 19% of cats have naturally occurring antibodies against RBC antigens outside the AB system

Feline blood type systems

• Before any blood transfusion. . .

• Cats must be crossmatched and blood typed

• Crossmatching is done to find out if the patient, the recipient, has Ab that will attack the red blood cells that it receives from the donor

Crossmatching

• Major XM

  • Recipient serum added to Donor red blood cells

  • Asks the question: Does recipient have Abs against donor’s red blood cells?

  • If yes a major transfusion reaction will occur and the recipient could die

Crossmatch results

• Macro-agglutination

  • Test tube or on slide

• Micro-agglutination

  • On slide under microscope

Evaluate every crossmatch for BOTH macro-

and micro-agglutination

Canine blood groups

• Dog erythrocyte antigens or DEA

  • DEA 1, 3, 4, 5, 6, 7, 8

  • RBCs are either positive or negative for an antigen

  • Co-dominantly inherited except for DEA 1

  • DEA 1 has an autosomal dominant inheritance

  • Dogs are either DEA 1+ or DEA 1-

  • About half the canine population is DEA 1+ (47-65% depending upon breed and geography)

DEA 1

• Most clinically important red cell surface Ag or blood type

• Giving a DEA 1- dog DEA 1+ blood causes the DEA 1- dog to make very strong anti-DEA 1 antibodies

• If this DEA 1- dog were to receive another DEA 1+ blood transfusion, a life-threatening hemolytic transfusion reaction could occur

• Recommended to blood type all dogs for the presence of DEA 1 before any blood transfusion

Other DEAs

• 3,4,5,6,7,8

• Clinically not as much of a problem as DEA 1

• Why? Examples:

  • 97% of dogs are DEA 4+, rare to have a DEA 4- dog

  • Naturally occurring Ab’s exist in some dogs to DEA 3 and 5 but they are weak and not many dogs are 3 or 5+

  • Don’t have blood typing reagents for these, only for research purposes

Canine blood typing

• Only test for DEA 1

• Most blood donors are DEA 1 negative

Canine transfusions

• First-time transfusions are considered safe

  • No need to crossmatch because

  • Dogs do not carry clinically significant naturally occurring antibodies

    • These Abs are weak and the reaction is mild

• Only need to blood type the recipient; donors are already typed

• If your patient needs a blood transfusion always ask the owner if the dog has ever had a blood transfusion before

Canine blood types

• If the answer is yes (more than two weeks ago):

  • This dog has Abs against the red cells that it previously received

  • (Donor red cells are foreign to the recipient, WBCs present them to T cells, who present to B cells, plasma cells make Ab against those red cells on average between 4-14 days post exposure)

Canine blood types

• If this dog now needs a blood transfusion again and receives the same blood type it received for the first transfusion. . .

• What do you think will happen?

  • Strong hemolytic transfusion reaction

• If the owner answers yes, my dog had a blood transfusion last year, what test should be done between this dog and the donor blood you have?

  • Major crossmatch

Canine blood groups

• Dal blood type

  • Strong anti-Dal Abs are made

  • High percentage of Dalmatians, Dobermans, Shih tzus in North America are Dal negative

  • All other purebred dogs are Dal+ and typically used as blood donor dogs

  • Dal negative dogs at high risk for incompatible blood transfusions if need more than one transfusion

  • Dal  and DEA 1 blood typing recommended for Dalmatians, Dobies, shih tzus

Neonatal isoerythrolysis in cat

• ”Fading kitten syndrome”

• Type B Queen mated to Type A Tom

  • Type A kittens will receive anti-A Abs in the queen’s milk

  • Anti-A Ab are present regardless of first or second pregnancy

  • Cats used for breeding should be blood typed before mating

Neonatal isoerythrolysis in foals

• In the horse most important blood type is A^a

• If an A^a – mare is mated to an A^a + stallion the foal may be A^a +

  • Mare will make anti-A^a Ab

• First pregnancy usually not a problem

  • Abs only get into bloodstream after drinking them during first 16 hrs, well before Mom makes them

• If this mating happens again and the foal is A^a +ve

  • High levels of anti-A^a Ab are ingested by the A^a + foal during first 16 hrs of nursing

  • Foal’s red cells will be hemolyzed or destroyed

• Horses are blood typed before mating