Abstract Details

Title Upregulated complement receptors correlate with Fc gamma receptor 3A-positive natural killer cells (NK) and natural killer-T cells (NKT) in neuromyelitis optica spectrum disorder.

Topic Autoimmune Neurology

Presentation(s) S50 - Autoimmune Neurology: NMOSD (3:54 PM-4:06 PM)

Poster/Presentation
Number 003

Background

Inhibition of terminal complement in neuromyelitis optica spectrum disorder (NMOSD) using eculizumab helps prevent relapses, but the exact mechanism of action of the drug remains unclear. Similarly, genetic variants in the Fc Gamma receptor 3A (FCGR3A), also known as CD16, are correlated with outcomes in NMOSD, but the immune cells expressing those CD16 are unknown. We compared CD16 expression on immune cells modulated by complement activity in Natural Killer (NK) cells and Natural Killer-T (NKT) cells in NMOSD to disease and normal-healthy controls.

Objective To clarify if NK and NKT cells are activated via complement receptors in NMOSD.

Design/Methods

Peripheral blood cell (PBMC) samples from 45 patients with NMOSD with aquaporin 4 (AQP4)-IgG, 18 disease controls, and 19 normal controls were analyzed for CD16 expression and complement receptors in vitro.

Results

At baseline, the number of NKT cells was increased in NMOSD (p < 0.001), but the proportion that was CD16 positive was lower compared to normal and disease controls (p=0.0012). NK cell count was normal, but the ratio that was CD16 positive was also significantly lower (p < 0.001). In both NK cells and NKT cells from NMOSD, C5 complement receptor expression was much higher than normal and disease controls (p < 0.001 for both). We also evaluated activation markers CD69 and CD83, which were also significantly higher in NK and NKT cells from NMOSD patients. FCGR3A p158 V/V genotype group in NMOSD patients showed decreased NK cell proportion with activation, and fewer CD16 expressed NKT cells than the F/F genotype group.

Conclusions

Our results support an immunopathogenesis model in which complement pathway activation in NK/NKT cells upregulates CD16 expression that binds to antibody/antigen complexes. In the context of NMOSD, these complement-sensitive cells may be responsible for the escalating autoimmune activity.

Authors/Disclosures
Shuhei Nishiyama, MD, PhD (Tohoku University Graduate school of Medicine) PRESENTER	Dr. Nishiyama has nothing to disclose.
	No disclosure on file
Itay Lotan, MD (MASSACHUSETTS GENERAL HOSPITAL)	Dr. Lotan has nothing to disclose.
Friedemann Paul (Charite Universitatsmedizin in Berlin)	The institution of Dr. Paul has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Mitsubishi Tanabe PC (MTPC). The institution of Dr. Paul has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Aarhus University. Dr. Paul has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Alexion. Dr. Paul has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Roche. Dr. Paul has received personal compensation in the range of $0-$499 for serving on a Scientific Advisory or Data Safety Monitoring board for Sanofi Genzyme. Dr. Paul has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for UCB Pharma. Dr. Paul has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for CELGENE. Dr. Paul has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for Bayer. Dr. Paul has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for Novartis. Dr. Paul has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for ACRELION. Dr. Paul has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for Viela Bio. Dr. Paul has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for Alexion. Dr. Paul has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for Roche. Dr. Paul has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for Pfizter. Dr. Paul has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for Merck Serono. The institution of Dr. Paul has received personal compensation in the range of $500-$4,999 for serving as an Editor, Associate Editor, or Editorial Advisory Board Member for Springer.
Michael Levy, MD, PhD, FAAN (Massachusetts General Hospital/Harvard Medical School)	Dr. Levy has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Mitsubishi Pharma. Dr. Levy has received personal compensation in the range of $500-$4,999 for serving as a Consultant for UCB Pharma. Dr. Levy has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Sanofi. Dr. Levy has received personal compensation in the range of $5,000-$9,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Alexion. Dr. Levy has received personal compensation in the range of $5,000-$9,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Horizon. Dr. Levy has received personal compensation in the range of $5,000-$9,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Genentech. Dr. Levy has received personal compensation in the range of $500-$4,999 for serving as an Editor, Associate Editor, or Editorial Advisory Board Member for Elsevier. Dr. Levy has received personal compensation in the range of $10,000-$49,999 for serving as an Expert Witness for Various law firms. The institution of Dr. Levy has received research support from National Institutes Health.