Abstract
Hoya (sea-squirt) asthma is an occupational asthma induced by inhalation of antigenic substances contained in the body fluid of hoyas. It was first noted in a worker of a cultured oyster farm. Long term hyposensitization of hoya asthma patients was conducted and the relationship between the production of specific IgG antibody and the effect of this therapy was studied. Specific IgG antibody was measured by radioimmunoassay using Protein A-Sepharose CL-4B and 125I labeled purified hoya antigen “Ei-M”.
1) The anti-Ei-M IgG values of 15 healthy cases, 31 healthy oyster workers, 109 non-hyposensitized hoya asthma cases and 270 hyposensitized hoya asthma cases were 1.3±0.23%, 2.0±0.60%, 2.3±1.03% and 8.8±8.11%, respectively. In comparison with healthy cases, the value of the three other groups were significantly higher (P<0.001). The anti-Ei-M IgG values of hyposensitized cases were significantly higher (P<0.001) than those of healthy workers and nonhyposensitized cases, but there was no difference between healthy workers and non-hyposensitized cases (P<0.2).
2) In the non-hyposensitized patients, the the anti-Ei-M IgG value stayed at a low level without any relation-ship to whether the cases were engaged in oyster work or not. Asthmatic symptoms developed in these cases while engaged in the work.
3) When hyposensitization was conducted, the anti-Ei-M IgG value made a rapid increase immediately after commencement of the treatment and after 5-6 months the value reached a peak, followed thereafter by an almost constant level. The value did not decrease even during the off-season as long as maintenance therapy was performed
4) Cases continuing to engage in oyster work with a low anti-Ei-M IgG value developed asthmatic symptoms, but cases showing a high anti-Ei-M IgG value did not develop asthmatic attacks even when exposed to antigen.
The foregoing results suggest that the effects of hyposensitization therapy are brought about mainly by production of the specific IgG antibody.
