ETIOLOGY AND PATHOGENESIS

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  Three mechanisms of drug-related immunologic injury to red cells are defined:

  
  

  — Hapten/drug adsorption involving drug-dependent antibodies

  
  

  — Ternary complex formation involving drug-dependent antibodies

  
  

  — Induction of autoantibodies that react with red cells in the absence of the inciting drug

  
  
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  Drug-related nonimmunologic protein adsorption may also result in a positive direct antiglobulin test without red cell injury.

  
  
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  Table 24–1 lists the drugs implicated in the production of a positive direct antiglobulin test and accelerated red cell destruction.

  
  
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  Table 24–2 summarizes the four mechanisms of drug-induced immune interaction with the red cell surface.