| Source | Observation | References |
| Salivary glands | FoxP3 expression is associated with the severity of glandular inflammation Inverse relationship between glandular and circulating FoxP3+ cells Lower FoxP3+ cells correlate with adverse predictors for lymphoma development CD25low/-GITR+ T cells are present in mononuclear cell infiltrate High expression of IL-17 and IL-17R High expression of IL-6, IL-21, IL-22, and IL-23 CD4+, CD8+, mast cells, and DN T cells produce IL-17 IL-17 is associated with the severity of glandular damage DN T cells are associated with GCs | [21, 23] [21] [21] [26] [50–52] [50, 52–57] [55, 60, 61] [51, 52] [61] |
| Saliva/tears | Increased levels of IL-17 in saliva Increased levels of IL-17 in tears No association between salivary IL-17 and glandular damage | [64] [65–67] [64] |
| Serum | Increased levels of IL-17 Increased levels of IL-6, IL-21, and IL-23 IL-17 prevalence is dependent on disease duration Serum IL-17 is higher in patients with MSG-GCs | [50, 51, 69, 70] [52, 53] [70] [69] |
| Peripheral blood | Altered Treg cell percentage (increased, decreased, or comparable percentages with respect to HD) Inverse correlation between the percentage of Treg cells and CRP, ESR, RF, and IgG No differences in Treg cell percentage according to ESSDAI and SSDAI Expansion of functionally suppressive CD25low/-GITR+T cells Suppressive CD25low/-GITR+T cell percentage are expanded in inactive pSS Increase of circulating CD4+Th17 cells Increase of circulating IL-17+DN T cells | [17–26] [19] [25, 26] [26] [26] [26] [51, 59–61] [60, 61] |
| Intrinsic cell abnormalities | The Vbeta repertoire of pSS Treg cells is polyclonal and not significantly restricted as compared with that in controls IL-17-producing DN T cells are totally insensitive to dexamethasone in vitro IL-17A gene displays an association with GC status | [17] [60] [91] |
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