TWENTY-FIFTH ANNUAL EASTERN FISH HEALTH WORKSHOP MARCH 10-13, 2000   Immunohistochemical Detection Of Channel Catfish (Ictalurus punctatus) Immunoglobulin In Formalin-Fixed Tissues     Joanne Maki1, Corrie Brown2, Harry Dickerson1   1Department of Medical Microbiology & Parasitology, College of Veterinary Medicine, University of Georgia, Athens, GA 30602; 2Department of Pathology, College of Veterinary Medicine, University of Georgia, Athens, GA 30602     Monoclonal antibodies (mAbs) specific for channel catfish immunoglobulin (CF-Ig) have identified CF-Ig+ cells by flow cytometry, indirect immunofluorescence and immunohistochemistry of frozen tissue sections (Ellsaesser et al., 1985; Lobb and Clem, 1982; Ainsworth et al., 1990 and Xu, Ph.D. dissertation, 1995). Unfortunately, mAbs are often specific for epitopes destroyed by reducing conditions such as formalin fixation. In earlier studies, a rabbit polyclonal antibody (Ab) against CF-Ig was shown to lack specificity due to the production of cross reactive anti-carbohydrate antibodies common to many fish cells (Yamaga, 1978). To detect CF-Ig+ cells in formalin-fixed tissues, we recently developed and tested a goat polyclonal anti-CF-Ig antibody. Pre-immune and post-immunization goat IgG were purified from sera using a Protein A/G column. The purified anti-CF-Ig Ab detected Ig+ cells in formalin-fixed, paraffin-embedded catfish tissues at a dilution equivalent to 130 ng/ml. A biotinylated anti-goat Ab and a biotin-avidin-enzyme complex were used to indirectly identify target cells with very low background staining. Pre-incubating the goat anti-CF-Ig Ab with purified catfish Ig abolished the reagent’s activity in ELISA as well as in situ. Sections of catfish head kidney, spleen, renal kidney, liver, gill, skin, and intestine were evaluated for CF-Ig+ cells. This reagent is currently being used to identify catfish Ig+ cells in situ by electron microscopy.   Return to 25th Annual Eastern Fish Health Workshop Return to Leetown Science Center Home Page