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HEMATOLOGY, ONCOLOGY, ALLERGY,

AND IMMUNOLOGY

May be further divided (see Table 9.5)

■ Autoimmune (warm and cold antibody) hemolytic anemia

■ Alloimmune (transfusion reaction) hemolytic anemia

■ Drug-induced hemolytic anemia

ALLOIMMUNE

Mediated through antibodies against foreign RBC antigens either through

transfusion of ABO incompatible blood or sensitization to maternal Rh factor

in hemolytic disease of the newborn

DRUG-INDUCEDHEMOLYTICANEMIA

Mediated through formation of drug-induced antibodies, hapten formation,

or immune complex formation

Hemolysis stops with cessation of drugs.

DIAGNOSIS

■ Microspherocytes on peripheral smear

■ Positive Coombs test

TREATMENT

■ Treat underlying cause or stop implicated medication/transfusion.

■ Warm antibody hemolytic anemia may respond to high-dose corticos-

teroids, IV gamma globuline, cytotoxic agents, or splenectomy.

■ Cold antibody hemolytic anemia is generally not responsive to medical

therapy, therefore primary treatment is avoidance of cold.

TABLE 9.5. Classification of Immune-Mediated Hemolytic Anemia

Autoimmune

Warm antibody IgG autoantibody Lymphoproliferative disorders

Bind at body temperature

Cold antibody IgM autoantibody Acute: Mycoplasma pneumonia or

(cold agglutinins) Epstein-Barr infection

Bind at cool temperatures Chronic: lymphoma or Waldenstrom

macroglobulinemia

Alloimmune Antibodies against foreign Transfusion reaction

RBC antigens Hemolytic disease of newborn

Drug-induced Three possible mechanisms:

IgG autoantibody α-Methyldopa, cephalosporins,

ibuprofen

Hapten formation Penicillin, cephalosporin

Immune complex formation Amphotericin B, INH, quinidine,

sulfonamides