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84 / Chapter 6 Haemolytic anaemias

4 Immunosuppression may be tried if steroids and/ at the tip of the nose, ears, fingers and toes caused
or splenectomy have failed. This may be with by the agglutination of red cells in small vessels.

drugs or monoclonal antibodies. Azathioprine, Laboratory findings are similar to those of warm

cyclophosphamide, chlorambucil, ciclosporin AIHA except that spherocytosis is less marked, red
and mycophenolate mofetil have been tried. cells agglutinate in the cold (Fig. 6.9 b) and the DAT
5 Monoclonal antibodies. Anti - CD20 (rituximab) reveals complement (C3d) only on the red cell
has produced prolonged remissions in a propor- surface. The serum shows a high titre of “ cold ”

tion of cases and anti - CD52 (Campath - 1H) has autoantibodies to red cells.
been tried successfully in a few cases. Treatment consists of keeping the patient warm
6 High - dose immunoglobulin has been used but and treating the underlying cause, if present.

with less success than in ITP (see p. 336) . Alkylating agents such as chlorambucil or purine

7 It may be necessary to treat the underlying nucleoside analogues (e.g. fl udarabine) may be

disease, e.g. chronic lymphocytic leukaemia or helpful in the chronic varieties. Both anti - CD20
lymphoma. (rituximab) and anti - CD52 (Campath - 1H) have

8 Folic acid is given in severe cases. been used. Rituximab is particularly eff ective when

9 Blood transfusion may be needed if anaemia is there is an associated B - lymphoproliferative disease.
severe and causing symptoms. The blood should Splenectomy does not usually help unless massive

be the least incompatible and if the specifi city of splenomegaly is present. Steroids are not helpful.
the autoantibody is known, donor blood is Underlying lymphoma should be excluded in
chosen that lacks the relevant antigen(s). Th e ‘ idiopathic ’ cases.
patients also readily make alloantibodies against Paroxysmal cold haemoglobinuria is a rare syn-
donor red cells. drome of acute intravascular haemolysis after expo-
sure to the cold. It is caused by the Donath – Landsteiner

Cold a utoimmune h aemolytic a naemias antibody, an IgG antibody with specificity for the P
In these syndromes the autoantibody, whether blood group antigens, which binds to red cells in the
monoclonal (as in the idiopathic cold haemaggluti- cold but causes lysis with complement in warm con-
nin syndrome or associated with lymphoprolifera- ditions. Viral infections and syphilis are predisposing
tive disorders) or polyclonal (as following infection, causes and the condition is usually self - limiting.
e.g. infectious mononucleosis or Mycoplasma pneu-
monia) attaches to red cells mainly in the peripheral
Alloimmune h aemolytic a naemias
circulation where the blood temperature is cooled

(Table 6.5 ). The antibody is usually IgM and In these anaemias, antibody produced by one indi-
binds to red cells best at 4 ° C. IgM antibodies are vidual reacts with red cells of another. Two impor-

highly effi cient at fixing complement and both tant situations are transfusion of ABO - incompatible
intravascular and extravascular haemolysis can blood and Rh disease of the newborn which are
occur. Complement alone is usually detected on considered in Chapters 29 and 30 . Th e increased
the red cells, the antibody having eluted off the cells use of allogeneic transplantation for renal, hepatic,

in warmer parts of the circulation. Interestingly, in cardiac and bone marrow diseases has led to the
nearly all these cold AIHA syndromes the antibody recognition of alloimmune haemolytic anaemia
is directed against the ‘ I ’ antigen on the red cell resulting from the production of red cell antibodies
surface. In infectious mononucleosis it is anti - i. in the recipient by donor lymphocytes transferred
in the allograft.
Clinical f eatures
The patient may have a chronic haemolytic anaemia

Drug - i nduced i mmune h aemolytic
aggravated by the cold and often associated with
a naemias
intravascular haemolysis. Mild jaundice and

splenomegaly may be present. The patient may Drugs can cause immune haemolytic anaemias via
develop acrocyanosis (purplish skin discoloration) three mechanisms (Fig. 6.10 ):