Combination treatment with GW788388 and IL-23 sustains increased Th17 cell levels in the spleen and lymph nodes of mice with premalignant oral lesions. Starting from Week 6 of 4NQO administration, when premalignant oral lesions were detectable on the tongue, mice were initiated on treatment with diluent, GW788388, IL-23 or both GW788388 and IL-23. After 2 months of these treatments, spleens and lymph nodes were collected and were surface immunostained for CD4 and stained intracellularly for IL-17. Shown are percentages of spleen cells and lymph node cells staining positive for CD4 plus IL-17. ** = p <0.01, *** = p <0.001.