Type ii reaction

The type II reaction is based on the formation of antigen-specific antibodies. In contrast to the IgE antibodies in the immediate reaction, however, IgG antibodies are formed. These bind self-antigens of rare exogenous antigens.

After binding of antibodies (IgG, IgM) to cellular antigens, lysis of the target cell occurs by activation of the complement cascade and by the action of cytotoxic cells (killer cells, platelets, eosinophil and neutrophil granulocytes, monocytes/macrophages). While the sensitization phase with the formation of corresponding antibodies takes about 5-10 days, the effector phase lasts about 2-3 days until clinical symptoms appear.

Typical diseases with an underlying type II allergy:

• allergic haemolytic anaemia
• Immune thrombocytopenic purpura (thrombocytopenic purpura; ITP)
• Drug-induced thrombocytopenia (drugs bind to thrombocytes (e.g. penicillin, vancomycin) and lead to sensitization with specific IgG antibodies and to cytolysis.
• Heparin-induced thrombocytopenia (HIT)
• Agranulocytosis
• Transfusion incidents
• Goodpasture's Syndrome

1. Biedermann T (2018) Basic principles of allergy and intolerance reactions. In: Braun-Falco`s Dermatology, Venerology Allergology G. Plewig et al. (Hrsg) Springer Verlag S 448-449