Isolation and partial characterization of lymphocyte surface immunoglobulins from the channel catfish (Ictalurus punctatus, Rafinesque)

Abstract

Lactoperoxidase catalysed radioiodination, detergent lysis and specific immunoprecipitation were used to recover the surface immunoglobulins (SIg) from channel catfish lymphocyte sub-populations. The molecular weight and antigenic nature of blood, spleen and anterior kidney lymphocyte SIg were compared by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and autoradiography. These procedures revealed quantitative and qualitative differences between the lymphocyte sub-population SIg. Analysis of the serum immunoglobulin and lymphocyte SIg by SDS-PAGE showed that only one class of immunoglobulin heavy chain (analogous to mammalian (mu)-chain) was present and that the lymphocyte SIg (mu)-chain was approximately 3,700 daltons heavier than the (mu)-chain of catfish serum immunoglobulin. Autoradiographic analysis of the lymphocyte SIg showed that two immunoelectrophoretically distinct isotype components occurred on the surface of catfish blood lymphocytes. The SIg of spleen and anterior kidney lymphocytes do not appear to contain distinct isotype components. A possible differentiation sequence within the catfish lymphocyte sub-populations is hypothesized.