Abstract
BackgroundStudies suggest that free-ranging bottlenose dolphins exhibit a suppressed immune system because of exposure to contaminants or microorganisms. However, due to a lack of commercially available antibodies specific to marine mammal immune cell surface markers, the research has been indecisive. The purpose of this study was to identify cross-reactive terrestrial-specific antibodies in order to assess the changes in the immune cell populations of dolphins under human care and free-ranging dolphins. The blood and PBMC fraction of blood samples from human care and free-ranging dolphins were characterized by H&E staining of cytospin slides and flow cytometry using a panel of terrestrial-specific antibodies.ResultsIn this study, we show that out of 65 terrestrial-specific antibodies tested, 11 were cross-reactive and identified dolphin immune cell populations within their peripheral blood. Using these antibodies, we found significant differences in the absolute number of cells expressing specific markers within their lymphocyte and monocyte fractions. Interestingly, the peripheral blood mononuclear cell profile of free-ranging dolphins retained an additional population of cells that divided them into two groups showing a low (<27%) or high (>56%) percentage of smaller cells resembling granulocytes.ConclusionsWe found that the cross-reactive antibodies not only identified specific changes in the immune cells of free-ranging dolphins, but also opened the possibility to investigate the causal relationship between immunosuppression and mortality seen in free-ranging dolphins.
Highlights
Studies suggest that free-ranging bottlenose dolphins exhibit a suppressed immune system because of exposure to contaminants or microorganisms
Peripheral blood mononuclear cells (PBMC) isolated from peripheral blood display differences between dolphins under human care and free-ranging dolphins Similar to humans and other species, dolphin peripheral blood smears showed a heterogeneous population of white bloods cells (WBCs): monocytes, lymphocytes, and granulocytes, including neutrophils, basophils and eosinophils (Fig. 1a)
The absolute number of PBMCs isolated from peripheral blood of free-ranging dolphins was significantly higher with an average of 3.1 × 106 PBMCs/ml ranging from 1.3 to 9.0 × 106 PBMCs/ml (Table 1)
Summary
Studies suggest that free-ranging bottlenose dolphins exhibit a suppressed immune system because of exposure to contaminants or microorganisms. The purpose of this study was to identify cross-reactive terrestrial-specific antibodies in order to assess the changes in the immune cell populations of dolphins under human care and free-ranging dolphins. Nouri-Shirazi et al BMC Veterinary Research (2017) 13:78 found changes in immunological parameters, such as absolute number of eosinophils and lymphocytes [6] and lymphocyte proliferation in dolphins exposed to certain contaminants [7,8,9] that may adversely lead to cell anergy or autoimmune diseases [7, 8]. Other studies showed an inverse correlation between contaminant levels and immune cells and their function in marine mammals, such as absolute number of lymphocytes, eosinophils, and monocytes [6], lymphocyte proliferation [10,11,12,13], phagocytosis [14], and nonspecific [15] and specific [16] immune responses. The fact that the incidence of tumors is increasing in free-ranging dolphins suggests that tumors can evade immune surveillance due to changes in their immune parameters [17, 18]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
