Lecture 6 9/5/24 Flashcards
What is a blood group?
related group of antigens on the RBC surface
What is a blood group antigen?
specific antigens within a blood group
What is a blood type?
phenotypic expression of a blood group
What are acquired alloantibodies?
antibodies produced after exposure to an RBC antigen not present on the individual’s own cells
What are naturally-occurring alloantibodies?
antibodies produced without prior exposure to RBC antigens
Which conditions can lead to acquired alloantibodies?
-blood transfusion
-pregnancy
-blood-derived products
What are the consequences of alloantibodies?
-agglutination
-hemolysis
What are the clinical implications of alloantibodies?
-transfusion reactions
-neonatal isoerythrolysis
What are the characteristics of major transfusion reactions?
-recipient has antibodies against antigen on donor RBCs
-life-threatening
-can cause intravascular hemolysis, hypotension, and DIC
-risk on first transfusion
What is the main characteristic of minor transfusion reactions?
can occur even with compatible blood typing and crossmatching
What are the characteristics of neonatal isoerythrolysis?
-most common in foals, also seen in kittens
-occurs in neonates who acquire antibodies against their own RBC antigens through colostrum
-antigen-negative dam is bred to antigen-positive sire
What is blood typing?
detection of specific antigens on RBCs
What is crossmatching?
detection of antibodies in the serum of one animal that bind to antigens on RBCs from another animal
What are the characteristics of blood typing?
-whole blood sample used
-reagent contains antibodies against a specific RBC antigen
-positive reaction leads to agglutination
-negative reaction shows no agglutination
What are the most clinically important blood groups?
dogs: DEA 1; no naturally occurring antibodies
-cats: AB system with types A, B, AB; naturally-occurring antibodies are common
horses: Aa and Qa: most antigenic
What result is seen in crossmatching if the two animals are incompatible?
agglutination and/or hemolysis
What are the two samples used in a major crossmatch?
-donor RBCs
-recipient serum
What are the practical implications of blood typing and crossmatching in horses?
-blood typing for horses is not available in house and is rarely done at labs
-must rely on crossmatching when performing transfusion medicine
-want to screen horses that enter blood donor programs; prefer horses negative for Aa, Qa, Ac, and Ca
What are the practical implications of blood typing and crossmatching in dogs?
-typically do not have naturally-occurring antibodies to RBC antigens
-crossmatching is almost always compatible for first transfusion
-blood typing and crossmatching recommended for subsequent transfusions
What are the practical implications of blood typing and crossmatching in cats?
-often have naturally-occurring antibodies
-always blood type, even before first transfusion
What are the characteristics of crossmatch diagnosis of neonatal isoerythrolysis?
-uses foal RBCs and mare serum
-agglutination/hemolysis indicates positive result for NI
