Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content +++ INTRODUCTION ++ In autoimmune hemolytic anemia (AHA), shortened red blood cell (RBC) survival is the result of host antibodies that react with autologous RBC. AHA may be classified by whether an underlying disease is present (secondary) or not (primary or idiopathic) (Table 22–1). AHA may also be classified by the nature of the antibody (Table 22–2). “Warm-reacting” antibodies are usually of the immunoglobulin G (IgG) type, have optimal activity at 37°C, and bind complement. “Cold-reacting” antibodies show affinity at lower temperatures (see Chap. 23). Occasionally, mixed disorders occur with both warm and cold antibodies. Warm antibody AHA is the most common type. ++Table Graphic Jump LocationTABLE 22–1CLASSIFICATION OF WARM-ANTIBODY–MEDIATED AUTOIMMUNE HEMOLYTIC ANEMIA (AHA)View Table||Download (.pdf) TABLE 22–1 CLASSIFICATION OF WARM-ANTIBODY–MEDIATED AUTOIMMUNE HEMOLYTIC ANEMIA (AHA) On basis of presence or absence of underlying or significantly associated disorder Primary or idiopathic AHA (no apparent underlying disease) Secondary AHA Associated with lymphoproliferative disorders (eg, Hodgkin or non-Hodgkin lymphoma) Associated with the rheumatic disorders, particularly systemic lupus erythematosus Associated with certain infections (eg, Mycoplasma pneumoniae) Associated with certain nonlymphoid neoplasms (eg, ovarian tumors) Associated with certain chronic inflammatory diseases (eg, ulcerative colitis) Associated with ingestion of certain drugs (eg, α-methyldopa) ++Table Graphic Jump LocationTABLE 22–2MAJOR REACTION PATTERNS OF THE DIRECT ANTIGLOBULIN TEST AND ASSOCIATED TYPES OF IMMUNE INJURYView Table||Download (.pdf) TABLE 22–2 MAJOR REACTION PATTERNS OF THE DIRECT ANTIGLOBULIN TEST AND ASSOCIATED TYPES OF IMMUNE INJURY Reaction Pattern Type of Immune Injury IgG alone Warm-antibody autoimmune hemolytic anemia Drug-immune hemolytic anemia: hapten drug adsorption type or autoantibody type Complement alone Warm-antibody autoimmune hemolytic anemia with subthreshold IgG deposition Cold-agglutinin disease Paroxysmal cold hemoglobinuria Drug-immune hemolytic anemia: ternary complex type IgG plus complement Warm-antibody autoimmune hemolytic anemia Drug-immune hemolytic anemia: autoantibody type (rare) Source: Williams Hematology, 9th ed, Chap. 54, Table 54–4. +++ ETIOLOGY AND PATHOGENESIS ++ AHA occurs in all age groups, but the incidence rises with age, in part because the frequency of lymphoproliferative malignancies increases with age. In primary AHA, the autoantibody often is specific for a single RBC membrane protein, suggesting that an aberrant immune response has occurred to an autoantigen or a similar immunogen; a generalized defect in immune regulation is not seen. In secondary AHA, the autoantibody most likely develops from an immunoregulatory defect. Certain drugs (eg, α-methyldopa) can induce specific antibodies in otherwise normal individuals by some unknown mechanism. These subside spontaneously when the drug is stopped. The red cells of some apparently normal individuals may be found coated with warm-reacting autoantibodies similar to those of patients with AHA. Such antibodies are noted in otherwise normal blood donors at a frequency of 1 in 10,000. A few develop AHA. RBC autoantibodies in AHA are pathogenic. RBCs that lack the targeted antigen have a normal survival in the presence of the antibody. Transplacental ... Your Access profile is currently affiliated with '[InstitutionA]' and is in the process of switching affiliations to '[InstitutionB]'. Please click ‘Continue’ to continue the affiliation switch, otherwise click ‘Cancel’ to cancel signing in. Get Free Access Through Your Institution Learn how to see if your library subscribes to McGraw Hill Medical products. Subscribe: Institutional or Individual Sign In Username Error: Please enter User Name Password Error: Please enter Password Forgot Password? Forgot Username? Sign in via OpenAthens Sign in via Shibboleth You already have access! Please proceed to your institution's subscription. Create a free a profile for additional features.