BTLA and systemic lupus erythematosus: However, recent studies have shown that BTLA and HVEM can also be expressed on regulatory T cells (Tregs) in patients with systemic lupus erythematosus (SLE), and their interaction inhibits the function of these cells, thereby promoting disease progression. This suggests that blocking the BTLA/HVEM complex may have therapeutic potential not only in cancer immunotherapy but also in the treatment of autoimmune diseases; however, further research is needed.