However, when patients were classified according to their age (< or >60 years old), we noticed a decrease in BTLA levels in DN from lupus patients older than 60 years of age (MFI: 12,330 ± 2010 for patients > 60 years old vs. 19,820 ± 1440 for patients < 60 years old; p < 0.05) (Figure 2D). This evidence concerns the gene BTLA and systemic lupus erythematosus.