Immunocompetence in a long-lived ectothermic vertebrate is temperature dependent but shows no decline in older adults

Laura M. Zimmerman, Amanda Wilson Carter, Rachel M. Bowden, Laura A. Vogel

In ectothermic (cold-blooded) vertebrates, temperature affects all of the body’s functions, including immune function. Age is a second factor that can affect immune function in vertebrates. Typically, the immune system gets worse with age in vertebrates. But it is unknown if these factors, age and temperature, can have interacting effects on the immune system. We set out to test this using the red-eared slider turtle as our model system. The immune functions that we tested involved B cells, a type of white blood cell. In turtles, B cells can produce antibodies in the presence or absence of antigen stimulation. Further, they can also engulf potential pathogens through a process called phagocytosis. We tested the ability of B cells from sliders to produce antibodies and phagocytose antigens at varying temperatures that the turtles would experience in nature.

We found no interaction between age and temperature on any of our measures of B cell function. However, we did find a significant effect of temperature, with decreased function at temperatures below 29°C. Interestingly, we did not find any negative impact of age on the measured immune functions. This rather unusual finding warrants more investigation into the immune responses of the red-eared slider turtle.

Image caption: Photo provided by authors.
This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. You can find the As Accepted version here.

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