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. 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. Key message Immunoblotting analysis showed common bands at 17 kDa for lettuce latex and patient serum. The 17 kDa protein bands were identified as kirola‐like protein by LC‒MS/MS. We purified the kirola‐like protein.