The serum IgE level was determined by the RIST (Radioimmunosorbent Test) in 18 cases of sea-squirt asthma (A), 10 cases of ordinary bronchial asthma (B), 9 healthy oyster farm workers (C) and 8 healthy individuals (D), and also determination was made with the RAST (Radioallergosorbent Test) with Ei-2 or Gi-2 coupled Sepharose 4B (named Ei-2or Gi-2 RAST value respectively) using the same serum. The results obtained were as follows: 1. Both the Ei-2 and Gi-2 RAST values were significantly high in Group (A), but failed to demonstrate significant differences among Group (B), (C) and (D). 2. The RIST values showed Group (A) to be significantly higher than (B), (C) and (D), and (B) was higher than (C), but there was no significant difference between (C) and (D). 3. A significant correlation was observed only between the Ei-2 and Gi-2 RAST values for Group (A), whereas no correlation could be demonstrated for (B), (C) nor (D). 4. A tendency for correlation could be observed between the Ei-2 or Gi-2 RAST values and their RIST values for (A), particularly, the correlation between the Gi-2 RAST and RIST values were significant. However, there was no correlation between the two values for subjects in the other groups. 5. In the cases of (A), Ei-2 value was inhibited by preincubation with Gi-2. Based on the facts that there is a great difference in molecular weight between the Ei-2 and Gi-2 antigens and their responses to mucous membrane tests differ in (A), but the respective RAST values for (A) are high and a good correlation exists between the two and also Ei-2 RAST values are inhibited by preincubation with Gi-2, then the assumption can be made that the substance which is common to both the Ei-2 and Gi-2 antigens and actively reacts to skin tests, possesses an antigenic determinant of almost identical structure.
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