Cooperative Fish and Wildlife Research Units Program: West Virginia
Education, Research and Technical Assistance for Managing Our Natural Resources

Smith, C.R., V.S. Blazer, C.A. Ottinger, H.L. Walsh and P.M. Mazik. 2023. Immune function of wild smallmouth bass collected from sites within the Chesapeake Bay watershed, 2016-2021. U.S. Geological Survey Data Release,


Abstract: The utility of a functional immune assay for wild smallmouth bass (Micropterus dolomieu) was evaluated in context with other aspects of host and environmental health. The mitogenesis assay utilized imaging flow cytometry with advanced machine learning for cell cycle analyses, 5-ethynyl-2’-deoxyuridine (EdU) incorporation into replicating DNA for detection of proliferation and an anti-smallmouth bass IgM monoclonal antibody to distinguish lymphocyte type. The assay was field-tested with fish collected from three sites, in two river drainages within West Virginia, as part of fish health assessments occurring in spring (pre-spawn; April – May) and fall (recrudescence; October – November). Leukocytes were isolated from anterior kidney tissue and exposed to lipopolysaccharide (LPS) from E.coli O111:B4 or mitogen-free media, which served as the negative control and a measure of unstimulated background lymphocyte proliferation as a baseline for wild fish. Mitogenic responses were dependent upon the collection site and season in which the fish were collected. Factors such as sex, age, tissue parasites, and macrophage aggregates were also evaluated. The differences in lymphocyte mitogenesis among smallmouth bass populations emphasizes the need for integrated assessments to determine not only environmental stressors but also infectious agents that may modulate the immune response in immunotoxicological studies.