Réactions d’hypersensibilité dues aux agents modifiant la réponse biologique ( biologicals)

Abstract

Adverse reactions induced by biological agents which are being used increasingly in the therapy of inflammatory diseases, autoimmune disorders and tumors are being observed more and more frequently. This is a consequence of both the growing number of indications and the increasing number of these substances. They have an intrinsic immunologic effect, due to their structure, to their structural similarity to physiological proteins, as well as to their capacity to act directly on the immune system. In addition, they can induce the production of anti-allotype or anti-idiotype antibodies, especially when they have an extensive murine sequence, but also through their humanized or human antibody components. The adverse reactions which they induce also depend on the structure of their target, which they can activate, inhibit or modify by other mechanisms. The principal adverse reactions are of type α, with a “cytokine release syndrome”, or of type β, with the production of IgG or IgE antibodies and subsequent immediate type reactions such as urticaria, anaphylaxis or serum sickness. Pre-existing antibodies directed against some of these agents may have been generated by ubiquitous cross-reacting epitopes. Local reactions occur frequently at the subcutaneous injection site of these agents; these reactions can sometimes be avoided by modifying the injection technique. The means of diagnosing such reactions are currently limited and their value has not yet been established on a large number of subjects. Continuation of this therapy is generally contraindicated due to the risk of severe complications.