Since the injection of recombinant Gal-9 induced the apoptosis of T cells and ameliorated systemic lupus erythematosus (SLE) in MRL-lpr lupus-prone mice20, we thought that Gal-9−/− BALB/c mice would demonstrate the aggravation of the disease. This evidence concerns the gene LGALS9 and systemic lupus erythematosus.