Cloning and immunobiochemical analyses on recombinant chymopapain allergen Cari p 2 showing pollen-fruit cross-reaction

Mol Immunol. 2021 Jun 29;137:42-51. doi: 10.1016/j.molimm.2021.06.010. Online ahead of print.

Abstract

Papaya is reported to trigger food and respiratory allergy. Here, we identified chymopapain Cari p 2 as an allergen that can sensitize atopic individuals through fruit consumption followed by respiratory hazards through pollen exposure. Recombinant Cari p 2 displayed IgE-reactivity with 78% of papaya allergic sera. rCari p 2 also displayed allergenic activity through basophil degranulation. rCari p 2 is correctly folded and showed irreversible denaturation in the melting curve. rCari p 2 displayed IgE-cross-reactivity with homologous cysteine proteases from kiwi and pineapple. Cari p 2 transcript was also detected in papaya pulps. rCari p 2 was resistant to pepsin digestion and retained IgE-reactivity after 60 minutes of pepsin digestion. In mouse model, rCari p 2 was found to elicit inflammatory responses in the lung and gastrointestinal epithelium. Hence, Cari p 2 is a newly characterized allergen with diagnostic and immunotherapeutic potential for managing allergic disorders in papaya sensitized individuals.

Keywords: Cari p 2; Chymopapain; Cross-reactivity; Papaya allergy; Recombinant allergen.