In contrast to the observed increase in BAFF levels, APRIL decreased significantly from a median of 9.25 ng/ml (range 0 to 182.3 ng/ml) to 3.34 ng/ml (range 0.99 to 175.7 ng/ml) during B-cell depletion in our SLE cohort (p < 0.05) (Figure 1b, Table 1). Here, TNFSF13 is linked to systemic lupus erythematosus.