Immunity and the red blood cell Flashcards
What are the types of immunity?
Naturally occuring antibodies - Blood group ABO
Alloantibodies - produced if wrong blood is given - Rh anti-D
Autoantibodies
What is the Rh system?
Most are Rh positive, on exposure to Rh a Rh- person will make anti D IgG antibodies, this can cause problems in pregnancy in particular haemolytic disease of the newborn. IgG antibodies do not cause agglutination instead lead to haemolysis
What is the forward group and what is it used for?
This is a blood test which identifies blood groups
Uses the patients RBC and known anti-A, B and D reagents are added
If they clot they rise to the top
What is the reverse group?
Patients plasma is used and know A B RBCs are used for agglutination
What is the antibody screen?
Clinically relevant antibodies are identified and appropriately negative blood is transfused
Ab are IgG so can cause extravascular haemolysis
How is the antibody screen done?
Patient plasma is taken, RBC with known antigens are added (large variety used)
The ab will coat the RBCs and anti IgG is added showing agglutination
What is the direct coombs test? How is it done?
Looks for antigen on the RBCs of patients
Antibodies to known antigens are added, anti-IgG also added to identify if any IgG is bound to RBCs via agglutination
What is the indirect coombs test and how is it done?
Looking for the Ab in the patients serum, add rbcs with known antigens into plasma and the add anti IgG
What are the 3 types of immune haemolytic anaemis?
Alloimmune
Drug induced
Autoimmun
What are the alloimmune mmune haemolytic anameias?
Haemolytic disease of the newborn
Transfusion reactions
What are the autoimmune haemolytic anaemias?
Warm AIHA Cold Agglutinin disease DLHA - Donath Lansteiner Haemolytic anaemia Mixed Type Dat negative AIHA
What is warm AIHA?
Removal of RBCs by the spleen - they are removed by the Kupffer cells
this is the most common type
What is Cold Agglutinin disease?
Worse in the winter, and at the peripheries
IgM antibody activates at low temperatures, bind to the RBC then cause lysis by complement opsonisation
What is DLHA?
Cold reacting IgG abnormally activates complement leading to intravascular haemolysis via MAC
This presents as haemoglobinuria after cold exposure
DAT positive for anti - C3
It is often related to syphilis or mycoplasma
What are the causes of AIHA?
Idiopathic
Secondary - in under 5s postviral (ITP), in older infections e.g. HIV and mycoplasma Hep, EBV
Neoplasms CLL, lymphoma and thymomas
