Kook‐Jin Lim’s scientific contributions

Background Silkworm pupa (SWP) food anaphylaxis has been described frequently in Asian countries. However, false-positive reactions by skin pricks and serum IgE (sIgE) tests to the extract complicate diagnosis, requiring identification of clinically relevant major allergens. Objectives In this study, we characterized a novel SWP allergen, Bomb m 4, a 30 kDa lipoprotein, and evaluated its diagnostic sensitivity. Methods Bomb m 4 was identified by a proteomic analysis. This recombinant (r)Bomb m 4 was overexpressed in Escherichia coli, and the IgE reactivity by ELISA was compared with other reported allergenic proteins: Bomb m 1 (arginine kinase), 27 kDa glycoprotein, Bomb m 3 (tropomyosin) using the serum samples from 17 SWP allergy patients and 11 asymptomatic sensitized subjects. Results rBomb m 4 specific IgE was recognized by all 17 SWP allergy patients. The 27 kDa glycoprotein and Bomb m 1 sIgE were found in 35.3% and 0%, respectively in the SWP allergic patients. ELISA sIgE reactivity increased significantly, when 4 M urea was added in serum samples. However, only 16% inhibition of sIgE reactivity to the whole SWP extract was exhibited by rBomb m 4, whereas more than 93% of self-inhibition of rBomb m 4 sIgE was obtained, possibly due to the low abundance of Bomb m 4 in the extract. Three linear epitopes (81-95, 191-205, and 224-238 residues) of rBomb m 4 were identified. These epitopes are shown to be released by pepsin digestion. ROC analysis showed the highest diagnostic value of Bomb m 4 followed by Bomb m 1, 27 kDa glycoprotein, and Bomb m 3. Conclusion Bomb m 4 is the major allergen of SWP allergy patients. It has cryptic epitopes which are exposed to IgE antibodies with digestive enzymes. This recombinant Bomb m 4 allergen permits exact diagnosis of SWP allergy.

Although specific IgE to the storage mite Acarus siro is often detected, there are no detailed studies on IgE reactivity to A. siro in Korea. This study was undertaken to investigate the cross-reactivity to the mite species Dermatophagoides pteronyssinus, Dermatophagoides farinae, Tyrophagus putrescentiae, and A. siro in Korean mite allergic patients. Specific IgE values were determined for the four mite species and a competitive inhibition test was performed for mite extracts using the ImmunoCAP system. The IgE value to D. farinae was the highest among the four mite species tested. There was a strong correlation in the IgE value between house dust mites (D. pteronyssinus and D. farinae) and between storage mites (A. siro and T. putrescentiae). IgE reactivity to A. siro was inhibited by D. farinae and T. putrescentiae extract. Dermatophagoides farinae extract was the strongest inhibitor of IgE binding to A. siro extract, indicating that IgE reactivity to A. siro extract is a cross-reaction caused by sensitization to D. farinae. Strong IgE reactive components were observed in D. farinae and T. putrescentiae extract by SDS-PAGE and IgE immunoblotting. However, no strong IgE-binding component was observed for A. siro. Dermatophagoides farinae is the main source of mite allergens that cause sensitization in Korea. Serum IgE from some of the house dust mite-sensitized patients showed positive responses to storage mite allergens by cross-reaction. Therefore, it is necessary to pay special attention to the diagnosis of mite allergies.