Autoimmune haemolytic anaemia (AIHA) is an
immune disorder caused by
antibodies directed against unmodified autologous red cells. The disorder may be a primary (idiopathic) or a secondary disease. The diagnosis is based on the presence of anaemia, signs of
haemolysis with
reticulocytosis, low
haptoglobin, increased
lactate dehydrogenase, elevated indirect
bilirubin, and a positive direct antiglobulin test (Coombs test). Sometimes, not all of these typical features are present. Most AIHA are caused by warm
antibodies, whereas cold
antibodies are less commonly detected. While half of the warm antibody-based AIHA are idiopathic anaemias, almost all cold antibody AIHA are secondary anaemias. Underlying diseases are Non Hodgkin's
lymphomas and systemic autoimmune disorders, and less frequently
organ transplantation,
infections, or solid
tumors. Moreover, AIHA is an important complication of treatment with
nucleoside analogs. Most patients with AIHA require
therapy. In warm antibody AIHA, standard first line
therapy are glucocorticosteroids with or without high dose
immunoglobulins, whereas
splenectomy is considered second-line
therapy. Response rates of primary AIHA to
corticosteroid therapy are high. After initial remission, the dose should be tapered down slowly and with caution, and in some cases, low-dose maintenance
therapy is required. The efficacy of standard
therapy is low in secondary AIHA that develops in
lymphoma patients, posttransplant patients, or
tumor patients. Among other immunosuppressive treatments,
rituximab (anti-CD20) appears to be highly effective in patients with warm antibody AIHA refractory to standard
therapy.
Mycophenolate mofetil is quite effective in AIHA patients with an underlying autoimmune or lymphoproliferative disease. Patients with
cold agglutinins are refractory to
steroids and
splenectomy. Half of these patients may respond to
rituximab, although responses usually are short-lived. Sometimes, AIHA that is associated with
malignant lymphomas or
tumors, disappears after successful anti-
lymphoma or anti-
tumor therapy.