Serum immunosuppressive acidic protein(IAP) was measured by single radial immunodiffusion method in 21 patients with neuroblastoma. Serum IAP of normal children was 382.3±133.6μg/ml(n=31)(mean ± SD). Serum IAP of patients with neuroblastoma correlated with clinical stage except stage IVS. It was significantly higher in patients with stage III and IV than in normal children. It was within normal range in patients with stage IVS. Our results suggested that immunological response of patients with stage IVS is not impaired. Serum IAP did not relate with histology of tumors and urin VMA, but did with serum LDH (r=0.483). It was found that serum IAP before treatment was higher in dead patients that in alive patients. In conclusion, serm IAP is an useful marker for neuroblastoma in anticipating the prognosis of these patients.
