BTLA and systemic lupus erythematosus: Due to the higher BTLA expression by lupus aTregs, the overlay of the BTLA/HVEM dot plots of a HC and a lupus patient, revealed an upward shift in lupus aTregs compared to HC aTregs (Figure 6C) and consequently, the calculated ratio of HVEM and BTLA expression on aTregs, which is of 3.6 ± 0.3 in HC is significantly decreased in aTregs from lupus patients (2.9 ± 0.3, p<0.05; Figure 6D) but not in other populations, such as naive CD4+ T cells.