Fig. 43.

Mechanisms of immune stimulation by drugs. a Hapten theory—a drug binds to self-proteins causing the immune system to recognize the protein–hapten complex as foreign. This may be followed by antigen uptake and processing by APCs creating peptides which are then covalently bound on MHC molecules on the APC surface for presentation to T cells. b Prohapten theory—the same process as for the hapten mechanism but the drug is first metabolized to a CRM which then acts as the hapten. c The parent drug is directly expressed in a MHC-dependent, non-covalent fashion to T cells (from Pichler et al. 2006)