Prevalence of Autoantibody Positivity and Associated Neuropathologies in the Oldest-old (P3-6.009)

Abstract

<h3>Objective:</h3> Our aim was to identify the prevalence of autoantibodies in an oldest-old cohort and to examine the relationship between presence of autoantibodies and neuropathologies found at postmortem. <h3>Background:</h3> Few studies have reported antibody prevalence in the oldest-old (age 90+). The association between autoantibody prevalence and presence of degenerative neuropathologies is yet to be studied. <h3>Design/Methods:</h3> Participants in an oldest old cohort (The 90+ Study) with at least one serum test result for antinuclear (ANA), antineutrophil cytoplasmic (ANCA), rheumatoid factor (RF), antithyroglobulin (ANTITG), and anti-double stranded DNA (DS-DNA) antibodies were examined. Test results were dichotomized (positive/negative). A subset had autopsy-confirmed neuropathology diagnosis for Alzheimer’s disease neuropathologic change, Lewy body disease, limbic-predominant age related TDP-43 encephalopathy, hippocampal sclerosis (HS), and aging-related tau astrogliopathy. We examined the relationship between neuropathology and antibody positivity using Fischer Chi-Square with Yates’ continuity correction. <h3>Results:</h3> Of 168 participants with serum results, 44% tested positive for ANA, 31% for ANCA, 21% for RF, 10% for ANTITG, and 6% for DS-DNA antibodies. In the subset with available postmortem results (N=19), antibody positivity rate was similar to the main cohort. Importantly, all participants with hippocampal sclerosis (N=4), were ANA positive and two (50%) had RF antibody. Also the single case with ANTITG antibody had HS. There were no other directions appearing from the other antibody and pathology results. <h3>Conclusions:</h3> We found that autoantibody positivity rate in an oldest old cohort was much higher than younger cohorts. Increased rate of autoimmunity is a potential explanation for this finding. Furthermore, all individuals with autopsy confirmed HS were ANA positive. In addition, half of HS cases had RF positivity and the only ANTITG positive case had HS. These results raise the possibility of an autoimmune etiology for this common degenerative pathology. <b>Disclosure:</b> Miss Leiby has nothing to disclose. Mr. Ramanathan has nothing to disclose. Ms. Ho has nothing to disclose. Mr. Siguenza has nothing to disclose. Dr. Ahmadi Jazi has nothing to disclose. The institution of Dr. Sajjadi has received research support from NIH.