Representative double immunodiffusion for three patients receiving syngeneic lymphocytes cultured with FCS. Center well, undiluted FCS; well 1, patient 12 preinfusion serum; well 2, patient 12 serum after first infusion; well 3, patient 2 preinfusion serum; well 4, patient 2 serum after first infusion; well 5, patient 8 preinfusion serum; well 6, patient 8 serum after the fourth infusion.