Meeting Abstract
We used blood samples from Mojave desert tortoises (Gopherus agassizii) to show that phagocytosis by lymphocytes occurs at a high but variable rate among individuals and can be quantified with and without species-specific reagents. Thus, this is an important new measure to add to the toolbox of ecological immunologists who are working with species of ectothermic vertebrates. Phagocytosis is an important aspect of innate immunity in which foreign elements are recognized by immune cells via receptors and are internalized, thereby clearing the body of potentially harmful pathogens. While lymphocytes are known to serve key functions within adaptive immunity, these cells have been previously shown to perform the innate immune function of phagocytosis in a wide variety of ectothermic vertebrates. These past studies have all relied on both expensive machinery and species-specific reagents. We optimized phagocytic assays for use in desert tortoises, using published protocols, species-specific reagents, fluorescent and confocal microscopy, and flow cytometry to verify and distinguish between innate binding of beads and true phagocytosis. However, we also show that simple Wright-Giemsa staining can be used to quantify binding and phagocytosis. Therefore, we show that this technique is widely applicable, with the recognition that some optimization-steps will need to be adjusted for use in different taxa. We offer suggestions for trouble-shooting optimization steps and hope to establish this technique as a common tool to assess immune function across species of ectothermic vertebrates.
