Identification of a 17 kDa protein that is a potentially novel antigen of lettuce‐associated respiratory allergy in farmers

BACKGROUND: We have identified and reported a novel antigen, nonprotein‐specific secreted EP1‐like glycoprotein (51 kDa), for lettuce‐related respiratory allergy. OBJECTIVE: We aimed to identify a novel antigen for lettuce‐related respiratory allergy that is different from epidermis‐specific secreted EP1‐like glycoprotein. METHODS: Immunoblotting was performed using an immunoglobulin E‐specific antibody. The antigen‐antibody reaction was confirmed by means of enzyme‐linked immunosorbent assaying. LC‒MS/MS analysis was carried out to detect a novel protein found in sera from 3 of 13 patients with lettuce‐related respiratory allergy. Finally, we purified a novel protein from Escherichia coli. RESULTS: Immunoblotting assays showed common bands of 17 kDa in the sera of 3 of 13 patients. An enzyme‐linked immunosorbent assay confirmed that the patient sera reacted with lettuce latex juice. A 17 kDa protein band that showed antigenic reactivity in 3 of 13 patient sera was identified as a kirola‐like protein by LC‒MS/MS. In addition, although we purified this protein, we failed to show the inhibitory effect. CONCLUSION: A 17 kDa protein that is a potentially novel antigen of lettuce‐associated respiratory allergy was identified. In further studies, we will focus on purifying this novel protein to diagnose lettuce allergy.