FAS and systemic lupus erythematosus: Moreover, BTLAlow DN B cells express significantly lower levels of HVEM than BTLA+ DN B cells (MFI: 3962 ± 388 for BTLAlow vs. 7982 ± 241 for BTLA+; p < 0.0001) but higher levels of CD95 (MFI: 3554 ± 412 for BTLAlow vs. 1710 ± 216 for BTLA+; p < 0.0001), both in lupus patients (Figure 3F,G) and HCs (Figure S3B), which is known to be induced upon B cell stimulation [24], indicating a more activated phenotype of these cells.