Sections View Full Chapter Figures Tables Videos 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 24–1). AHA may also be classified by the nature of the antibody (Table 24–2). "Warm-reacting" antibodies are usually of the IgG type, have optimal activity at 37°C, and bind complement. "Cold-reacting" antibodies show affinity at lower temperatures (see Chap. 25). Occasionally, mixed disorders occur with both warm and cold antibodies. Warm antibody AHA is the most common type. ++Table Graphic Jump LocationTABLE 24–1CLASSIFICATION OF WARM-ANTIBODY–MEDIATED AUTOIMMUNE HEMOLYTIC ANEMIA (AHA)View Table|Favorite Table|Download (.pdf) TABLE 24–1 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 (e.g., Hodgkin or non-Hodgkin lymphoma) Associated with the rheumatic disorders, particularly systemic lupus erythematosus Associated with certain infections (e.g., Mycoplasma pneumoniae) Associated with certain non-lymphoid neoplasms (e.g., ovarian tumors) Associated with certain chronic inflammatory diseases (e.g., ulcerative colitis) Associated with ingestion of certain drugs (e.g., α-methyldopa) ++Table Graphic Jump LocationTABLE 24–2MAJOR REACTION PATTERNS OF THE DIRECT ANTIGLOBULIN TEST AND ASSOCIATED TYPES OF IMMUNE INJURYView Table|Favorite Table|Download (.pdf) TABLE 24–2 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, 8th ed, Chap. 53, Table 53–4, p. 787. ++ ETIOLOGY AND PATHOGENESIS ++ AHA occurs in all age groups, but the incidence rises with age, probably 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 (e.g., 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. Transplacental passage of autoantibodies to a fetus ... GET ACCESS TO THIS RESOURCE Sign In Username Error: Please enter User Name Password Error: Please enter Password Forgot Username? Forgot Password? Sign in via OpenAthens Sign in via Shibboleth Get Free Access Through Your Institution Contact your institution's library to ask if they subscribe to McGraw-Hill Medical Products. What is MyAccess? Create a FREE MyAccess profile to: Use this site remotely Bookmark your favorite content Track your self-assessment progress and more!