AIHA - more in Immunological Disorders area !!!!!!! Flashcards
What does AIHA stand for ?
Autoimmune haemolytic anaemia
What are the general, clinical symptoms of AIHA?
Very low Hb levels
Positive DAT
What is the indirect Coombs test ? and briefly describe how it is carried out.
We have a recipients sample which contains red cell antibodies. Donor red cell of known phenotypes are used to find what antibodies are present.
Human anti-globulin reagent is added to cause agglutination if there is a positive result.
In the direct Coombs test, is there an incubation stage?
No
What is the purpose of the direct Coombs test?
Looking to see if a patient has any autoantibodies.
Outline what occurs in the direct Coombs test
Blood sample from a patient with AIHA antibodies are attached to antigens on the red blood cell surface.
The patients red blood cels are washed and then incubated with anti-human antibodies.
Red blood cells agglutinate as the antihuman antibodies form linked between red blood cells by binding to the human antibodies on red blood cells.
What is the main aim of a DAT test?
It tests for the type of antibody attached to the red cells.
What does ‘DAT’ stand for?
Direct antiglobulin test
What is the role of complement in AIHA?
IgG antibodies can attach to antigens on red cells and trigger the complement cascade.
What happens if complement occurs during AIHA and does not stop at the C3 stage?
Complement will continue to completion whee a channel is formed in the red cell membrane and cause lysis.
What causes complement in AIHA to sometimes end at the C3 stage?
Macrophages in the liver recognise complement is occurring and cause destruction of the autoantibodies by extravascular haemolysis.
What type of destruction occurs if complement continues past the C3 stage in AIHA?
Intravascular haemolysis. This releases free Hb and activates the complement cascade again. Leading to a positive feedback system.
What is the most common classification of AIHA?
Warm
What is the antibody type that causes warm AIHA?
IgG
