IMMUNOGLOBULIN BINDING-FACTOR - A NEW TUMOR-MARKER FOR PROSTATIC TUMORS

Human seminal plasma contains an immunoglobulin gamma binding factor ( IgBF) with an estimated molecular weight of 16 kD under reducing condi tion. IgBF was detected only in the prostate, including benign prostat ic hypertrophy (BPH) and neoplasm. The present study was performed to determine whether IgBF is a useful prostatic marker. Serum IgBF levels were measured in patients with prostatic tumors and in control patien ts without tumor by radioimmunoassay. Serum prostatic-specific antigen (PSA), the standard prostatic marker, was also determined. Serum IgBF levels in patients with prostate cancer were significantly higher tha n those in age-matched controls (P < 0.05). Also, patients with BPH te nded to have elevated IgBF levels than the controls, although the valu es were not statistically significant. In control patients, serum IgBF levels increased with advancing age. There was no correlation between serum levels of IgBF and PSA in patients with prostate cancer. Using cut-off level at 28.5 ng/ml (2 S.D. above the mean IgBF level of age-m atched control), the sensitivities were 41.2% (7/17) for prostate canc er, 23.1% (6/26) for BPH, and 5.6% (1/18) for control patients. In con clusion, serum IgBF is a useful marker in the diagnosis of patients wi th prostatic tumor, and in evaluating the course of treatment. (C) 199 4 Wiley-Liss, Inc.