Interleukin-2 immunotherapy in children. Immunotherapy with interleukin (IL)-2 possesses great potential in the treatment of immune-mediated diseases and cancers. However, only a few reports on a small number of children have appeared in the literature. From March 1988 to March 1989, 11 children and adolescents were treated with IL-2. They included 1 patient with hepatocellular carcinoma, 1 with hepatoblastoma, 6 with childhood atopic dermatitis, and 3 with juvenile rheumatoid arthritis. The dosages ranged from 10,000 to 50,000 U/kg every 8 hours by intravenous drip. The following side effects were observed: anorexia, fever, and chillness (100%), general malaise (82%), irritability (64%), diarrhea (100%), nausea and vomiting (73%), weight gain (82%), edema (82%), abdominal distension (73%), oliguria (82%), cough (91%), dyspnea (27%), pleural effusion (40%), hypotension (82%), skin eruption (82%), oral ulcer (18%), enlarged liver (73%) liver function abnormalities (82%), renal function impairment (36%), electrolyte imbalance (73%), anemia (91%), thrombocytopenia (54%), leukopenia (18%), and eosinophilia (73%). Immunologically, numbers of natural killer cells were increased and natural killer and lymphokine-activated killer cell activities were augmented after IL-2 treatment. There was a tendency for serum levels of IL-2 and receptor IL-2 to decrease, especially in patients with atopic eczema. Ten patients (91%) completed one course (9 to 12 days) of therapy, and the remaining patient interrupted the treatment because of intolerable adverse effects. Clinically, complete remission for 3 months was obtained in 1 juvenile rheumatoid arthritis patient, transient improvement (2 to 6 weeks) in all atopic dermatitis patients, minor response in the hepatoblastoma patient, and no response in the patient with hepatocellular carcinoma. 