Pathomechanisms of dextran-induced anaphylactoid/anaphylactic reactions in man.

Immune complex-mediated (type III) anaphylaxis is shown to be the pathomechanism of severe dextran-induced anaphylactic reactions in man. Mild reactions may be either antibody-dependent or not. Patients with severe reactions have regularly high titers of preformed, circulating dextran-reactive antibodies and represent a small subpopulation of high responders to dextran. Upon infusion of clinical dextran, noxious immune complexes are formed, leading to mediator release and symptoms of anaphylaxis. Consequently, application of the hapten inhibition principle is recommended for prevention of such reactions.