Halofuginone ameliorates systemic lupus erythematosus by targeting Blk in myeloid-derived suppressor cells

•HF alleviates the disease progression of systemic lupus erythematosus.•HF rescues the mRNA expression of Blk in MDSCs from lupus mice by NF-κB pathway.•HF enhances the kinase activity of Blk in MDSCs from lupus mice by directly binding.•Blk promotes the apoptosis of MDSCs through ERK signaling pathway.