The results we obtained showed that peripheral blood NK cytotoxic activity and interleukin-1 beta and interleu-kin-12 production were significantly down-regulated in patients with endometriosis with respect to controls, and this matched with higher serum concentrations of PCBs and p,p′-DDE in the same patients (Quaranta et al. 2006). Here, IL1B is linked to endometriosis.