Production of anti-Id following immunization using a combination of CpG ODN and soluble GM-CSF. Mice were immunized with 50 μg of Id-KLH as a single subcutaneous dose mixed in aqueous solution with GM-CSF, CpG ODN, or both. Blood was obtained weekly, and serum was evaluated for the presence of anti-Id IgG by ELISA. Normal mouse serum supplemented with a known concentration of monoclonal anti-Id was used as a standard. Three mice were included in each group. (□) Id-KLH + GM-CSF; (•) Id-KLH + CpG ODN; (▪) Id-KLH + GM-CSF + CpG ODN.