SOCS-1 deficiency in macrophages causes hyperproduction of IL-12p40 and TNF in response to multiple stimuli. Resident peritoneal macrophages from healthy 4-week-old Socs1^lox/-LysM-cre mice (▪) and Socs1^lox/- nontransgenic mice (□) as controls were cultured for 48 hours in the presence of LPS, IFN-γ, TNF, or IL-1. Culture supernatants were then assayed for (A) IL-12p40 or (B) TNF by ELISA. The data represent the mean ± SEM of 3 experiments. Statistical significance (Mann-Whitney test): ^*P < .05 or ^**P < .001 compared with Socs1^lox/- nontransgenic.