The Structural Properties of Israeli Carp ( Cyprinus carpio L. ) Immunoglobulin

Choi, Sang Hoon; Woo, Jong Kyu; Jang, Yong Suk; Oh, Chan Ho

Abstract

Serum immunoglobulins from Israeli carp (I. carp) were purified using affinity chromatography. Fish were immunized with purified mouse IgG, and the specific fish antibodies purified from the immune serum on a mouse IgG-immobilized agarose gel. Rabbit anti-carp Ig (Raclg) antibodies were produced following hyperimmunization with mlgG specific I. Carp Ab. SDS-PAGE analysis under reducing condition showed that I. carp Ig (clg) were composed of two u-like heavy chains with about 82 and 50 kD, respectively and one light chain with about 25 kD. On immunoblotting analysis, however, Raclg failed to react with light chain. When both protein A and protein G purified normal clg were compared with mlgG specific clg, no significant structural differences among them were observed. To investigate if there is any homology between other fish Ig molecules, cross-reactivity of Raclg against Ig molecules from 6 different fish sera and mouse control serum was checked on immunoblotting analysis. As a result, Raclg responded to only carp and tilapia Ig molecules, indicating that both tilapia and carp are very closely associated, especially, in the genetic basis of immunoglobulin structure. In flow cytometry study, Raclg appeared to recognize 45.8% of carp Ig+, 14.5% of catfish Ig+ and <5% of tilapia Ig+ cells. The result suggest the heterogeniety between receptor immunoglobulins on B-like lymphocytes and soluble immunoglobulins in serum. It is crucial to obtain pure fish immunoglobulins to produce reagent antibodies as tools for the study of their specific immune response.