Fish surface mucin hypersensitivity

Most reports of allergy to fish describe systemic symptoms upon ingestion of fish muscle or contact urticaria in commercial fish handlers. We report three recreational fishermen with symptoms of asthma, angioedema, rhinitis and urticaria upon exposure to surface mucin from bluegills (Lepomis machrochirus). All three had symptoms upon handling bluegills. Subsequently, two of them experienced wheezing and/or angioedema while in proximity to contaminated fishing clothing. One of them later developed symptoms upon eating bluegills. Prick skin testing was positive to crude bluegill surface mucin in all three individuals and to bluegill and cod muscle in one.

Bluegill surface mucin was defatted in ether and acetone and extracted in phosphate buffered saline. Sodium dodecyl-polyacrylamide gel electrophoresis (SDS–PAGE) showed at least 20 distinct protein bands by Coomassie Blue staining. Many of these were glycoproteins by periodic acid schiff (PAS) staining. Immunoblotting showed at least seven IgE binding protein bands with molecular weights between 10 and 100 kDa.

Radioallergosorbent (RAST) assay using a bluegill surface-mucin solid phase demonstrated that serum IgE binding in the three individuals was 4–25 times that of pooled serum from nonatopic controls. IgE binding using a serum pool from the three allergic patients was inhibited by extracts of bluegill mucin and muscle and cod muscle but not by tuna, crab or peanut.

Our results demonstrate that bluegill surface mucin contains specific glycoproteins which bind IgE in sensitive individuals. Hypersensitivity to these surface proteins may cause systemic allergic symptoms.