Background: CD4 ⁺ T cell subpopulations play a crucial role in the pathogenesis of systemic lupus erythematosus (SLE). Both numerical and functional disturbances have been reported in patients with adult-onset SLE [1,2], while little is known about their status in untreated late-onset SLE.

Objectives: To explore the changes and clinical significance of circulating CD4 ⁺ T cell subpopulations in patients with untreated late-onset SLE.

Methods: Peripheral blood samples and clinical information were collected from 55 patients with late-onset SLE (≥50 years), 195 patients with adult-onset (18-49 years), and 160 healthy controls. All patients were newly diagnosed and untreated. Percentages and absolute numbers of CD4 ⁺ T cell subsets were determined by flow cytometric analysis.

Results: Patients with late-onset SLE had lower SLEDAI scores than those with adult-onset SLE. The absolute numbers of circulating Treg (CD4 ⁺ CD25 ⁺ Foxp3 ⁺ ), Th17 (CD4 ⁺ IL-17 ⁺ ), Th1 (CD4 ⁺ IFN-γ ⁺ ) and Th2 (CD4 ⁺ IL-4 ⁺ ) cells in patients with late-onset SLE were lower than those in age-matched healthy controls, while the percentages of Treg cells in patients with late-onset SLE also decreased significantly. In addition, the ratios of Th17/Treg were higher in late-onset SLE patients than those in age-matched healthy controls. However, the ratios of Th17/Treg were lower in patients with late-onset SLE than those in adult-onset SLE patients.

Conclusion: Patients with late-onset SLE show the decreased numbers of Treg cells and the immune imbalance of Th17/Treg. However, the imbalance of Th17/Treg in late-onset SLE patients was milder than that in adult-onset SLE patients, which may be associated with lower disease activity.

REFERENCES: [1] Li H, Boulougoura A, Endo Y, Tsokos GC. Abnormalities of T cells in systemic lupus erythematosus: new insights in pathogenesis and therapeutic strategies. J Autoimmun. 2022; 132:102870.

[2] Chen M, Chen X, Wan Q. Altered frequency of Th17 and Treg cells in new-onset systemic lupus erythematosus patients. Eur J Clin Invest. 2018; 48(11):e13012.

Acknowledgements: NIL.

Disclosure of Interests: None declared.