Carica papaya pollen allergy

Background: Carica papaya (CP) trees are widely cultivated in tropical and subtropical areas; however, CP pollen allergy has not been previously described. Objective: To study patients with CP pollen hypersensitivity. Methods: A CP pollen extract was elaborated. Skin prick tests (SPTs) with this extract, as well as with commercial papaya fruit and papain extracts, were performed. Specific IgE levels to CP pollen, papaya fruit, and papain were determined. Specific conjunctival challenge tests to the CP pollen extract were also performed. RAST inhibition studies among CP pollen, papaya fruit, and papain were carried out. Twenty atopic patients were used as a control group for in vivo and in vitro tests. Results: Six patients with clinical histories of seasonal rhinoconjunctivitis or bronchial asthma in relation to CP trees exposure, suggestive of IgE-mediated respiratory allergy, were studied. Commercial SPT and specific serum IgE to papaya fruit and papain were positive in our patients. An IgE-mediated hypersensitivity to a CP pollen extract was demonstrated in all patients, by means of SPTs, specific serum IgE determinations, and conjunctival challenge tests. Control atopic subjects showed negative SPTs, specific IgE, and conjunctival challenge tests to the CP pollen extract. On PAST inhibition studies using CP pollen extract in solid phase, a significant crossreactivity was found among CP pollen, papaya fruit, and papain. Conclusions: Our study suggests that papaya flower pollen is able to induce respiratory IgE-mediated;allergy. The existence of common allergens among papaya flower pollen, papaya fruit, and papain has been demonstrated by PAST inhibition.