108.4 Saturday, Jan. 7 Humoral immunity to lipopolysaccharide in a long-lived ectotherm ZIMMERMAN, L. M.*; CLAIRARDIN, S. G.; PAITZ, R. T.; HICKE, J. W.; VOGEL, L. A.; BOWDEN, R. M.; Il. St. Univ.; Il. St. Univ.; Il. St. Univ.; Il. St. Univ.; Il. St. Univ.; Il. St. Univ. firstname.lastname@example.org
Immunosenescence, a decrease in immune function with age, does not affect all immune responses in the same manner. In humans, specific antibody responses decrease with age while non-specific antibodies increase. This reduction in specific antibody responses has been viewed as a contributor to the increase of mortality and morbidity with increasing age. Like humans, reptiles show an age-specific increase in non-specific antibodies, but unlike humans, reptiles of all ages have a less robust specific antibody response. Thus, the increase in non-specific antibodies may constitute an improvement in immune defense. However, the characteristics of the humoral response beyond quantity have not been determined. This study examined humoral immune responses in the red-eared slider turtle, Trachemys scripta, to lipopolysaccharide (LPS), a component of Gram negative bacteria. LPS is a T-independent antigen, meaning B cells can respond to it without help from T cells. Adult turtles were trapped and blood samples were taken at three points during the active season. Because red-eared sliders grow throughout their lifetime, plastron length was measured as a proxy for age. Leukocytes were isolated and their ability to produce antibodies in response to LPS stimulation was measured using an ELISpot assay. An ELISA was used to measure total immunoglobulin levels (Ig) and LPS-specific antibodies (Abs) in plasma. LPS Abs significantly increased with age, while antibody response to stimulation did not vary with age. Our results show no evidence of immunosenescence in humoral immunity to LPS. Therefore, in reptiles, unlike in humans, changes in humoral responses may not cause impairment in immune defense with age.