Mice (n=10/group, combined from two independent experiments) were immunized with OXY-sKLH with or without IL-4 depletion. After 3 immunizations, spleens and lymph nodes were collected and processed into a single cell suspension. Total and oxycodone-specific antibody secreting cells (ASCs) were measured by ELISPOT. A) Number of total IgG ASCs and B) oxycodone-specific ASCs normalized to total IgG ASCs. A second cohort of mice (n=4-6/group, from one independent experiment) were similarly immunized and bone marrow was collected on day 100. C) Total plasma cells in the bone marrow and D) oxycodone-specific plasma cells as a percent of total plasma cells were identified via flow cytometry. Data are mean±SEM. Statistical analysis performed via Student’s t test (A, C, D) or Welch’s t test (B). Statistical symbols: * p<0.05.