Dysregulated inflammatory responses of PGRN-deficient macrophages to bacterial endotoxin in vitro. (A) Reduced cytokine expression by PGRN-deficient macrophages in response to LPS. Quantitative RT-PCR at indicated times after exposure to 10 ng/ml LPS is shown. (B) Reduced cytokine release by PGRN-deficient macrophages in response to LPS. ELISAs were done with conditioned media collected 12 or 24 h after adding the indicated concentrations of LPS. (C) Enhanced IL-10 production by PGRN-deficient macrophages in response to LPS. IL-10 induction was determined as in A and B. Results are means ± SEM for triplicates from three to five similar experiments. *, P < 0.05 using the Student’s t test. ND, nondetectable.