IMMUNOGLOBULIN OF THE BROWN TROUT, SALMO-TRUTTA AND ITS CONCENTRATION IN THE SERUM OF ANTIGEN-STIMULATED AND NON-STIMULATED FISH

Immunoglobulin production in the primary and secondary immune response of brown trout to keyhole limpet haemocyanin has been investigated including the effect of dose size, route and number of injections, and the use of adjuvant. Antibody activity was found in the first fraction from Sephadex G200 and in the second from Sepharose 6B. Trout immunoglobulin had β2—Γ1 electrophoretic mobility, and Sapp of 16·7 and an approximate molecular weight of 670 000 daltons. It was sensitive to dithiothreitol and stable at 56°C for 30 min. Immunoglobulin concentrations were measured by single radial immunodiffusion with a specific rabbit antiserum. Sera from non‐injected trout had a mean immunoglobulin level of 7·3 ± 0·3 mg ml−1 which accounted for 10% of the total serum protein. Phosphate buffered saline‐injected controls contained 6·7 ± 0·2. In fish given a single injection the mean concentration ranged from 7·5 to 12·9 and in those given more than one injection from 12·6 to 16·8. The use of adjuvant resulted in higher immunoglobulin concentrations. Neither dose nor route had any significant effect on the primary response. However, in the secondary response the intramuscular route resulted in significantly increased immunoglobulin production. Copyright © 1979, Wiley Blackwell. All rights reserved