Abstract Details

Title B cell subsets and T follicular helper cells in myasthenia gravis thymus

Topic Autoimmune Neurology

Presentation(s) P4 - Poster Session 4 (5:30 PM-6:30 PM)

Poster/Presentation
Number 15-012

Objective To explore the pathogenic mechanism occurring in MG thymus, we examined B cell subsets as well as Tfh cell.

Background Functional and morphological abnormalities of the thymus occur frequently in the patients with myasthenia gravis (MG). However, it is unclear how immune cells develop autoimmune response in MG thymus. Some B cell subsets and T follicular helper (Tfh) cells play an important role in human autoimmune diseases.

Design/Methods Blood was collected from 10 healthy subjects and 14 MG patients. Thymuses were obtained from the patients undergoing cardiovascular surgery or thymectomy as follows: non-MG children, n=9; non-MG adults, n=12; MG patients, n=13. Seven MG patients received immunosuppressive drugs before thymectomy. Flow cytometry analyses were conducted with peripheral blood mononuclear cells and thymocytes. We compared Naïve B, Memory B, plasma blast, and Tfh cells. This study was approved by the Ethics Committee of the Tokushima University Hospital and the Chiba University Hospital.

Results

The circulating CD19⁺CD27⁺CD38^highCD180^- (plasma blast) cells was higher in MG patients compared to healthy subjects(p<0.01). MG patients revealed a significant increase of plasma blast in the thymuses than non-MG adults (p<0.01).The CD4⁺CXCR5⁺ICOS^high or CD4⁺CXCR5⁺PD-1^high (Tfh) cells were higher in MG patients and non-MG adults compared to non-MG children(MG patients vs. non-MG children, p<0.01; non-MG adults vs. non-MG children, p<0.05). Naive B cells, plasma blast cells, CD4+CXCR5+ICOShigh and CD4+CXCR5+PD-1high (Tfh) cells were slightly higher in MG patients without immunosuppressive therapy before thymectomy compared to MG patients with immunosuppressive therapy before thymectomy, but not significant.

Conclusions

We found the increase of plasma blast and unchanged Tfh cells in MG thymuses. We postulate that increased plasma blast contributes to produce the antibodies in MG thymus, but immunosupresive therapy before thymectomy might inhibit lymphoproliferative response leading to the ectopic germinal centers.

Authors/Disclosures
PRESENTER	No disclosure on file
Naoko Matsui, MD	No disclosure on file
	No disclosure on file
	No disclosure on file
	No disclosure on file
	No disclosure on file
	No disclosure on file
Takashi Yamamura, MD (National Inst of Neuroscience)	Dr. Yamamura has nothing to disclose.
Satoshi Kuwabara	Satoshi Kuwabara has nothing to disclose.
Yuishin Izumi, MD, PhD	No disclosure on file
Ryuji Kaji, MD, FAAN (Tokushima University Graduate School of Medicine)	Dr. Kaji has nothing to disclose.

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