Interleukin (IL)-17-producing pathogenic T lymphocytes co-express CD20 and are depleted by rituximab in primary Sjögren's syndrome: A pilot study

Compelling evidence suggests that interleukin (IL)-17 and IL-17-producing cells play a pivotal role in the pathogenesis of primary Sjögren's syndrome (pSS). We investigated phenotypical and functional effects of the anti-CD20 antibody rituximab (RTX) on circulating and glandular IL-17-producing T cells in pSS. RTX is able to deplete glandular IL-17+ CD3+CD4-CD8- double-negative (DN) and CD4+ Th17 cells as well as circulating IL-17+ DN T cells. A fraction of glandular and circulating IL-17+ DN cells and CD4+ T helper type 17 (Th17) cells co-expresses CD20 on the cell surface explaining, at least in part, such depletive capacity of RTX. The exposure to RTX does not rescue the in-vitro corticosteroid resistance of IL-17+ DN T cells. Our results support further the therapeutic role in pSS of RTX that, despite its B cell specificity, appears able to also hamper IL-17-producing T cells in this disease.