[Quantitative measurement of IAP (immunosuppressive acidic protein) in patients with retinoblastoma]

Immunosuppressive acidic protein (IAP) is a useful tumor marker for evaluating clinical course, therapeutic effectiveness, and prognosis of patients with various malignant tumors. In this report, we examined the serum IAP levels in 20 patients with retinoblastomas. In 6 cases, both preoperative and postoperative IAP values were examined, and in 14 cases the levels of this protein were postoperatively followed. Although 2 of 6 cases had higher levels of IAP than 500 micrograms/ml preoperatively, they had decreased within the normal range (less than 500 micrograms/ml) postoperatively. The mean IAP levels at 1-2 weeks before, 1-2 weeks after and 1 month after surgery were 422 +/- 225.1 micrograms/ml, 221 +/- 62.6 micrograms/ml, and 297 +/- 89.8 micrograms/ml, respectively, that means IAP decreased after enucleation. In 14 cases in which this protein was examined only postoperatively the value was 314.5 +/- 91.6 micrograms/ml. In one case with a level of 856 micrograms/ml of IAP before enucleation, pathological examination revealed invasion of retinoblastoma cells to the optic nerve and orbital fat. The high level of IAP might be related to the extraocular invasion. Since the level of serum IAP decreased after enucleation, these results suggested that immunological activities might change, even though tumor cells grew within the blood retinal barrier.