Drug-induced agranulocytosis: review of possible mechanisms, and prospects for clozapine studies.

Although toxicity and inborn errors of metabolism may also be involved, immunological reactions play an important role in the induction of drug-induced agranulocytosis. Drug-induced antibodies may lead to agranulocytosis by at least three different immunological mechanisms. Immune complexes may selectively adhere to granulocytes or their immature precursor cells, the drug may bind to the granulocytes as carriers of the immunogenic drug and finally the drug may induce antibodies directed to granulocyte-specific structures. The use and the interpretation of in vitro assays to detect drug-dependent antibodies against granulocytes or myeloid precursor cells are discussed. These assays will be used to detect a possible immunological mechanism involved in clozapine-induced agranulocytosis. Further studies will concern the identification of possible genetic risk factors associated with clozapine-induced agranulocytosis.