DR Medhat MRCP

Autoimmune hemolytic anemia (AIHA)
- It may be divided in to 'cold' and 'warm' types , according to at what temperature
the antibodies best cause hemolysis.
- It is most commonly idiopathic but may be secondary to a lymphoproliferative
disorder, infection or drugs.
- AIHA is characterized by a positive direct antiglobulin test (Direct Coombs' Test).
Features :
Cold AIHA
- Caused by IgM
- Causes hemolysis best at 4 0 C
- Hemolysis is mediated by
complement
- More commonly intravascular
Warm AIHA
- Caused by IgG
- Causes hemolysis at body temp.
- More commonly extravascular
e.g in spleen & other RES
Causes :
TTT
1. Neoplasia e.g lymphoma
2. Infections e,g mycoplasma ,EBV
Avoid exposure to cold
Plasma exchange in severe cases
Less response to steroids &
splenectomy (hemolysis is
intravascular)
1. Autoimmune : SLE(rarely mixed)
2. Neoplasia : N.H.lymphoma , CLL
3. Drugs : methyl dopa.
Steroids (tapering dose)
Splenectomy.
Immunosuppressive drugs.
Therapeutic plasmapheresis is considered MOST effective in Haemolytic anaemia
سؤال IgG) associated with Mycoplasma pneumonia (removal of IgM not
Coombs Test:
Direct Coombs Test
- Is used to detect these antibodies or complement proteins that are bound to
RBCs.
- A blood sample is taken and the RBCs are washed (removing plasma) and then
incubated with antihuman globulin (Coombs reagent) If this produces
agglutination of RBCs, the test is positive, an indication that antibodies (and/or
complement proteins) are bound to the surface of RBCs.
Indirect Coombs Test
- Is used in prenatal testing of pregnant women, and prior to blood transfusion.
- It detects antibodies against RBCs that are present unbound in the serum.
- In this case, serum is extracted from the blood, and the serum is incubated with
RBCs of known antigenicity ,If agglutination occurs, the test is positive.
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