Concluding, as for the work-up of this patient we would suggest: If correct skin testing with the locally present allergens in right concentrations is negative and there is no response to oral antihistamines then we would try a nasal steroid, nasal antihistamine or combination of the two. If this does not help and a brief burst of prednisone10 days does not relieve symptoms either then it's safe to say that the origin is not at all allergic. As to the workup, our next procedure would then probably be a rhinolaryngoscopy. It is possible that this patient has chronic rhino-sinusitis manifested solely as an itchy throat with occasional coughing. Another possibility would be laryngo-pharyngeal reflux which may be identified endoscopically. Finally, eventually the very rare causes- see above- could be considered.
Corticosteroids will inhibit phospholipase A2 thereby preventing the generation of substances which mediate inflammation, for example, prostaglandins. Corticosteroids also produce a marked, though transient, lymphocytopenia. This depletion is due to redistribution of the cells, the T lymphocytes being affected to a greater degree than the B lymphocytes. Lymphokine production is reduced, as is the sensitivity of macrophages to activation by lymphokines. Corticosteroids also retard epithelial regeneration, diminish post-inflammatory neo-vascularisation and reduce towards normal levels the excessive permeability of inflamed capillaries.