Background Smooth muscles hyperresponsiveness is a common feature in anaphylaxis and allergic diseases.
Objective The aim of the present work was to investigate the effect of in vitro passive sensitization with highly purified immunoglobulin GI (IgGl) on the responsiveness of tracheal, aortic, vas deferens and ileum smooth muscles.
Method Firstly, IgGl, obtained from actively sensitized BFA guinea-pigs, was purified by Protein A-Sepharose column and characterized by enzyme-linked immunosorbent assay (ELISA) and immunoelectrophoresis analysis. Concentration-response curves to spasniogens (acelylcholine for trachea and vas deferens, noradrenaline for aorta and histamine for ileum) were established before and after in vitro passive sensitizalion with IgGl.
Results Contractile responses and maximal contractions were significantly enhanced after passive sensitization for all the organs. Maximal contractions were significantly increased in the trachea (+46.7%), aorta (+51%), vas deferens (+114.2%) and ileum (+ 117.2%). At the end of the experiments, the application of the sensitizing antigen induced a significant Schultz-Dale reaction of the smooth muscles.
Conclusion The present results show that the in vitro application of purified IgGl can produce non-specific smooth muscle hyperreactivity and hypersensitivity. So, IgGl can be considered as the main factor involved in the genesis of sensitization-induced hyperresponsiveness, and probably play a great role in hyperreactivity observed during allergic diseases and anaphylaxis.