Finlay J A, Evans C L, Day J R, Payne J K, Mikolajczyk S D, Millar L S, Kuus-Reichel K, Wolfert R L, Rittenhouse H G
Hybritech Incorporated, San Diego, California 92196-9006, USA.
Urology. 1998 May;51(5):804-9. doi: 10.1016/s0090-4295(98)00107-1.
Human glandular kallikrein (hK2) is a protein that is 80% homologous to prostate-specific antigen (PSA), and, like PSA, is localized to the prostate. We developed a specific immunoassay for hK2 that can be used to evaluate its clinical diagnostic utility.
We developed monoclonal antibodies (mAbs) specific for hK2 by immunizing with hK2 and screening for clones reactive with hK2 and not PSA. Prototype sandwich assays using these mAbs were tested, and the optimum pair selected. Purified hK2 was used as standard and PSA cross-reactivity was assessed in the assay. Both hK2 and hK2-alpha1-antichymotrypsin (ACT) complexes have been identified in sera of patients with prostate cancer (PCa). Serum samples (n = 671) from healthy volunteers and patients with prostate disease were assayed for hK2 and PSA levels.
The assay had a detection limit of less than 0.12 ng/mL and a less than 0.5% cross-reactivity with PSA. The assay preferentially detected free hK2 with a 3.5-fold higher molar response than with hK2-ACT. The mean serum concentration of hK2 in normal control samples was low (0.33 and 0.37 ng/mL for normal healthy men and women, respectively) but was elevated in patients with prostate disease (0.86 and 6.77 ng/mL for patients with benign prostatic hyperplasia and PCa, respectively). Negligible cross-reactivity to hK2 was measured by Tandem PSA assays (Hybritech).
Significant concentrations of hK2, relative to PSA, were detected in human serum, especially in patients with prostate disease. Serum hK2 concentrations were not proportional to PSA concentration. Therefore, hK2 has the potential to be an independent and clinically useful marker for PCa.
人腺激肽释放酶（hK2）是一种与前列腺特异性抗原（PSA）有80%同源性的蛋白质，并且与PSA一样，定位于前列腺。我们开发了一种用于hK2的特异性免疫测定法，可用于评估其临床诊断效用。
我们通过用hK2免疫并筛选与hK2反应而不与PSA反应的克隆来开发针对hK2的单克隆抗体（mAb）。测试了使用这些mAb的原型夹心测定法，并选择了最佳配对。使用纯化的hK2作为标准品，并在测定中评估PSA交叉反应性。在前列腺癌（PCa）患者的血清中已鉴定出hK2和hK2-α1-抗胰凝乳蛋白酶（ACT）复合物。对健康志愿者和前列腺疾病患者的血清样本（n = 671）进行hK2和PSA水平检测。
该测定法的检测限低于0.12 ng/mL，与PSA的交叉反应性低于0.5%。该测定法优先检测游离hK2，其摩尔反应比hK2-ACT高3.5倍。正常对照样本中hK2的平均血清浓度较低（正常健康男性和女性分别为0.33和0.37 ng/mL），但在前列腺疾病患者中升高（良性前列腺增生和PCa患者分别为0.86和6.77 ng/mL）。通过串联PSA测定法（Hybritech）测得的与hK2的交叉反应性可忽略不计。
在人血清中检测到相对于PSA有显著浓度的hK2，尤其是在前列腺疾病患者中。血清hK2浓度与PSA浓度不成比例。因此，hK2有可能成为PCa的独立且具有临床效用的标志物。
