IL33 and systemic lupus erythematosus: Supernatants derived from the incubation of IC-treated SLE NETting neutrophils with (fl)IL-33 caused a significant, ST2L-dependent increase in p-IRF7 levels of pDCs, suggesting enrichment in bioactive IL-33, whereas an equivalent dosage of uncleaved (fl)IL-33 had the opposite effect (Figure 7E).