Autoimmune Haemolytic Anaemias: Causes, Symptoms & Treatment | PDF

Acquired immune haemolytic anaemias Autoimmune haemolytic anaemias Presented by Dr. Sahar Gamal Elbager Assistant Professor of Haematology UMST  Autoimmune haemolytic anaemias Autoimmune haemolytic anaemias (AIHAs) are caused by antibody production by the b...

Acquired immune haemolytic anaemias Autoimmune haemolytic anaemias Presented by Dr. Sahar Gamal Elbager Assistant Professor of Haematology UMST  Autoimmune haemolytic anaemias Autoimmune haemolytic anaemias (AIHAs) are caused by antibody production by the body againstits own red cells. Divided into „ warm ‟ and „ cold ‟ types according to whether the antibody reacts more strongly with red cells at 37 ° C or 4 ° C.  Warm autoimmune haemolytic anaemias The red cells are coated with immunoglobulin (Ig), therefore taken up by RE macrophages which have receptors for the Ig Fc fragment. Part of the coated membrane is lost so the cell becomes progressively more spherical to maintain the same volume. 3  Warm autoimmune haemolytic anaemias Is ultimately prematurely destroyed, predominantly in the spleen. When the cells are coated with IgG and complement (C3d,) or complement alone, red cell destruction occurs more generally in the RE system. 4  Clinical features The disease may occur at any age, in either sex Presents as a haemolytic anaemia of varying severity. The spleen is often enlarged. The disease tends to remit and relapse. It may occur alone or in association with other diseases. 5  Clinical features When associated idiopathic with thrombocytopenic purpura (ITP), it knownisas Evans ‟ syndrome. When secondary to systemic erythematosus the cells typicallylupus coated with immunoglobulin are complement. and 6  Laboratory findings 1. The haematological and biochemical findings are typical of an extravascular haemolytic anaemia with spherocytosis prominent in the peripheral blood 2. The DAT is positive as a result of IgG, IgG and complement or IgA on the cells and, in some cases, the autoantibody shows specificity within the Rh system. 3. The antibodies both on the cell surface and free in serum are best detected at 37° C. 7  Treatment 1. Remove the underlying cause. 2. Corticosteroids. Prednisolone is the usual first line treatment; 60 mg/day is a typical starting dose in adults and should then be tapered down. 3. Those with predominantly IgG on red cells do best whereas those with complement often respond poorly. Both to corticosteroids splenectomy. and 8  Treatment 4.Immunosuppression may be tried if steroids and/ or splenectomy have failed. This may be with drugs or monoclonal antibodies. 5.Monoclonal antibodies. Anti - CD20 has produced prolonged remissions in part of cases 9  Treatment 6.High - dose immunoglobulin has been used but with less success than in ITP. 7.It may be necessary to treat the underlying disease, e.g. chronic lymphocytic leukaemia or lymphoma. 8. Folic acid is given in severe cases. 9.Blood transfusion may be needed if anaemia is severe and causing symptoms. 10  Treatment The blood should be the least incompatible and if the specificity of the autoantibody is known, donor blood is chosen that lacks the relevant antigen(s). The patients also readily make alloantibodies against donor red cells 12  Cold autoimmune haemolytic anaemias In these syndromes the autoantibody, whether 1. Monoclonal (as in the idiopathic cold haemagglutinin syndrome or associated with lymphoproliferative disorders) 2. Polyclonal (as following infection, e.g. infectious mononucleosis or Mycoplasma pneumonia) Cold autoimmune haemolytic anaemias Ab attaches to red cells mainly in the peripheral circulation where the blood temperature is cooled. The antibody is usually IgM and binds to red cells best at 4 ° C. IgM antibodies are highly efficient at fixing complement and both intravascular and extravascular haemolysis can occur. Cold autoimmune haemolytic anaemias Complement alone is usually detected on the red cells, the antibody having eluted off the cells in warmer parts of the circulation. Interestingly, In nearly all these cold AIHA syndromes the antibody is directed against the „ I ‟ antigen on the red cell surface.  Clinical features The patient may have a haemolytic chronic anaemia aggravated and associated by with the intravascular cold haemolysis. often Mild jaundice and splenomegaly may be present. The patient may develop acrocyanosis (purplish skin discoloration) at the tip of the nose, ears, fingers and toes caused by the agglutination of red cells in small vessels.  Laboratory findings Laboratory findings are similar to those of warm AIHA except that spherocytosis is less marked, red cells agglutinate in the cold DAT reveals complement (C3d) only on the red cell surface. The serum shows a high titre of “ cold ” autoantibodies to red cells.  Treatment Treatment consists of keeping the warmand treating patient the present. underlying cause, Both anti - CD20 and anti - ifCD52 have been used. Rituximab is particularly effective when there is an associated B - lymphoproliferative disease. Splenectomy does not usually help unless massive splenomegaly is present. (A). Blood fi lm in warm autoimmune haemolytic anaemia. Numerous microspherocytes are present and larger polychromatic cells (reticulocytes). (b) Blood fi lm in cold autoimmune haemolytic anaemia. Marked red cell agglutination is present in fi lms made at room temperature. Thank you