CASP4 and rheumatoid arthritis: Moreover, we found that FADD secretion occurs in the absence of IL-1β secretion and LDH release (as observed for CASP4-KO THP-1 macrophages and primary RA monocytes) and, reciprocally, IL-1β secretion and LDH release occurs in the absence of FADD secretion (as observed for THP-1 monocytes in PBS buffer).