Background and aims CD8 T cell responses to viral pathogens is crucial for the prompt resolution of acute infections. SLE patients are more likely to have infections due to long-term glucocorticoid and immunosuppressive agent intake. The present study is to evaluate the potential anti-infection effect of low-dose IL-2 in SLE patients.

Methods Peripheral blood mononuclear cells from nine refractory SLE patients and 9 health controls (HCs). The disease activities were evaluated by rheumatologist. The frequencies of T cell subsets were assayed by flow cytometry. Virus-specific CD8 T cells responses were determined based on TNF-a IFN-g and Granzyme B producing CD8 T cells upon CMV-EBV-Flu(CEF) viral peptide pool stimulation.

Results Most patients showed good clinical responses after low-dose IL-2 treatment (7 out of 9). Clinical improvement was observed with SIR-4 response (6 out of 9), improved complement 3 and 4 serum level (9 out of 9) and decreased anti-ds-DNA serum level (8 out of 9). Functional profiling of CD8 T cells in low-dose IL-2 treated patients revealed increased frequencies of CEF viral peptide specific TNF-a⁺ and Granzyme-B⁺ CD8 T cells. Moreover, these patients showed stronger antigen-specific response demonstrated by an increased stimulated/non-stimulate TNF-a-producing CD8 T cells proliferation fold. Compared with HC, SLE patients showed significantly lower frequencies of CEF specific Granzyme-B producing CD8 T cell, and low-dose IL-2 significantly increased the frequency of these Granzyme-B⁺ CD8 T cells in SLE patients.

Conclusions Virus-specific antigen-specific CD8 T cell response could be enhanced upon this treatment which might be potentially valuable in anti-infection in SLE.