Isolation and characterization of an asthma-inducing sea-squirt antigen

An antigen capable of inducing asthmatic attack in patients with sea-squirt allergy has been isolated from body fluid of sea-squirt, Styela plicata, and designated as DIIIa. The chemical composition and the behavior in anion-exchange chromatography showed that the antigen was a weakly acidic glycoprotein. The weight-average molecular weight of DIIIa was estimated to be 9,880 by the sedimentation equilibrium method. This antigen was apparently discriminated from the previously isolated sea-squirt antigens, Gi-rep and Ei-M, by its activity to induce asthmatic attack and conjunctival congestion, though it gave a strongly positive reaction in skin tests against allergic patients, similarly to the previous antigens. From the cross-reaction of DIIIa to rabbit anti-Gi-rep and anti-Ei-M sera in vitro, it was confirmed that the antigen carried essentially the same antigenic determinant as Gi-rep and Ei-M, and this was termed type alpha determinant. Furthermore, the allergenic activities detectable in vivo and the reactivity to the rabbit antisera in vitro were simultaneously absorbed by immobilized immunoglobulin from anti-Gi-rep serum. Thus, it was suggested that the antigenic determinant responsible for the allergic reactions in vivo corresponded to that specified as type alpha in vitro on the basis of the reactivity against the rabbit anti-Gi-rep serum.