Histamine release upon adenosine 5'-monophosphate (AMP) nasal provocation in allergic subjects.

BACKGROUND Nasal provocation with adenosine 5'-monophosphate (AMP) elicits nasal symptoms in subjects with rhinitis. Histamine released from mast cells may play a part in AMP induced nasal responses. METHODS Symptoms of rhinitis were recorded and histamine release in the fluid obtained by nasal lavage after AMP, guanosine 5'-monophosphate (GMP), and placebo instillations was measured in nine subjects with allergic rhinitis and nine non-allergic controls in a double blind, randomised, placebo controlled study. RESULTS No symptoms or significant increases in histamine were observed after GMP and placebo challenge. Significantly higher levels of histamine were seen in the nasal lavage fluids of allergic subjects following AMP challenge than in nonallergic controls, the median (range) histamine concentration increasing from the baseline value of 1.62 (0.44-6.99) ng/ml to 6.45 (0.81-16.17) ng/ml at three minutes. No increase in histamine levels was seen in the non-allergic subjects in whom the median histamine concentration was 1.13 (0.29-4.25) ng/ml at baseline and 0.97 (0.31-5.89) ng/ml three minutes after AMP challenge. CONCLUSIONS AMP elicits an immediate rise in histamine levels in the nasal lavage fluid of allergic subjects compared with non-allergic individuals. These findings indicate that the exaggerated nasal response to adenosine may reflect mast cell priming in vivo, thus supporting its application as a potential new marker of allergic inflammation.