OBJECTIVES: To utilize a Luminex platform to examine multiple cytokines simultaneously as well as clinical laboratory testing to identify markers that predict acute pancreatitis severity in the pediatric population on admission. STUDY DESIGN: Patients (<19 years of age) prospectively enrolled over a 4-year period in a single institution acute pancreatitis database were included in separate derivation and validation cohorts. Plasma samples were obtained within 48 hours of admission and stored for analysis. Samples from mild acute pancreatitis and severe acute pancreatitis (moderately severe and severe combined) were analyzed using Luminex panels and C-reactive protein (CRP) testing. RESULTS: The derivation cohort examined 62 cytokines in 66 subject samples (20 control, 36 mild acute pancreatitis, 10 severe acute pancreatitis) and identified interleukin 6 (IL-6) (P = .02) and monocyte chemotactic protein-1 (MCP-1) (P = .02) as cytokines that were differentially expressed between mild and severe acute pancreatitis. Our validation cohort analyzed 76 cytokines between 10 controls, 19 mild acute pancreatitis, and 6 severe acute pancreatitis subjects. IL-6 (P = .02) and MCP-1 (P = .007) were again found to differentiate mild acute pancreatitis from severe acute pancreatitis. CRP values were obtained from 53 of the subjects, revealing a strong association between elevated CRP values and progression to severe disease (P < .0001). CONCLUSIONS: This study identified and validated IL-6 and MCP-1 as predictors of severe acute pancreatitis using 2 distinct cohorts and showed that CRP elevation is a marker of progression to severe acute pancreatitis. These biomarkers have not been extensively studied in the pediatric acute pancreatitis population. Our data allows for risk-stratification of patients with acute pancreatitis, and represent novel insight into the immunologic response in severe acute pancreatitis.