Transient Anti-TCRβ mAb Treatment Induces CD4⁺ T Cell Exhaustion and Prolongs Survival in a Mouse Model of Systemic Lupus Erythematosus

T cells play a critical role in the pathogenesis of systemic lupus erythematosus (SLE). Chronic T cell receptor (TCR) signalling induces T cell exhaustion, characterised by reduced capacity to induce tissue damage. Here, we investigated the therapeutic potential of the anti-TCRβ (H57-597) monoclonal antibody (mAb) in a mouse model of SLE. Four-month-old MRL/lpr mice exhibiting SLE phenotypes received 5 weekly doses of anti-TCRβ mAb or phosphate-buffered saline (PBS) vehicle control. Subsequently, mouse survival was monitored daily. On day 1 post the final dose of treatment, SLE pathogenesis was determined using histological staining and spot urine test. T and B cell states in the brain, kidney, and secondary lymphoid organs were determined by flow cytometry. Transient treatment of anti-TCRβ mAb significantly prolonged the survival of MRL/lpr mice. Accordingly, MRL/lpr mice in the anti-TCRβ mAb group exhibited decreased proteinuria scores and minimal renal pathological damage compared to the PBS control group. Flow cytometric analysis revealed that anti-TCRβ mAb treatment resulted in a reduction in the frequencies of CD4⁺ T cells and CD138⁺B220^lo/− plasma cells, plus an increase in Foxp3⁺ regulatory T cell frequency. Furthermore, CD4⁺ T cells from anti-TCRβ mAb treated mice exhibited elevated expression levels of PD-1 and TIM-3, with reduced IFN-γ production, indicative of an exhaustion-like phenotype. Therefore, transient administration of anti-TCRβ mAb treatment induces an exhaustion-like phenotype in CD4⁺ T cells, resulting in prolonged survival of MRL/lpr mice. Inducing autoreactive T-cell exhaustion holds promise as an attractive therapeutic approach for SLE.