Pancreatic secretory trypsin inhibitor Kazal type 1 (SPINK1) is a 6420 Da peptide produced by the pancreas, but also by several other tissues and many tumors. Some mutations of the SPINK1 gene, like the one causing amino acid change N34S, have been shown to confer susceptibility to recurrent or chronic pancreatitis. Detection of such variants are therefore of clinical utility. So far SPINK1 variants have been determined by DNA techniques. We have developed and validated an immunocapture-liquid chromatography-mass spectrometric (IC-LC-MS) assay for the detection and quantification of serum SPINK1, N34S-SPINK1, and P55S-SPINK1. We compared this method with a time-resolved immunofluorometric assay (TR-IFMA) for serum samples and primer extension analysis of DNA samples. We used serum and DNA samples from patients with acute pancreatitis, renal cell carcinoma, or benign urological conditions. With the help of a zygosity score calculated from the respective peak areas using the formula wild-type (wt) SPINK1/(variant SPINK1 + wt SPINK1), we were able to correctly characterize the heterozygotes and homozygotes from the samples with DNA information. The score was then used to characterize the apparent zygosity of the samples with no DNA characterization. The IC-LC-MS method for SPINK1 was linear over the concentration range 0.5–1000 μg/L. The limit of quantitation (LOQ) was 0.5 μg/L. The IC-LC-MS and the TR-IFMA assays showed good correlation. The median zygosity score was 1.00 (95% CI 0.98–1.01, n = 11), 0.55 (95% CI 0.43–0.61, n = 14), and 0.05 (range 0.04–0.07, n = 3) for individuals found to be wt, heterozygous, and homozygous, respectively, for the N34S-SPINK1 variant by DNA analysis. When DNA samples are not available, this assay facilitates identification of the N34S- and P55S-SPINK1 variants also in archival serum samples.

胰腺分泌型胰蛋白酶抑制剂Kazal 1型（SPINK1）是一种由胰腺产生的6420 Da肽，也可以由其他一些组织和许多肿瘤产生。SPINK1的某些突变该基因与引起N34S氨基酸改变的基因一样，已被证明对复发性或慢性胰腺炎易感。因此，检测此类变体具有临床实用性。迄今为止，已经通过DNA技术确定了SPINK1变体。我们已经开发并验证了用于血清SPINK1，N34S-SPINK1和P55S-SPINK1的检测和定量的免疫捕获液相色谱-质谱（IC-LC-MS）测定法。我们将该方法与用于血清样品和DNA样品的引物延伸分析的时间分辨免疫荧光测定法（TR-IFMA）进行了比较。我们使用了急性胰腺炎，肾细胞癌或良性泌尿科疾病患者的血清和DNA样本。借助于使用公式野生型（wt）SPINK1 /（变体SPINK1 + wt SPINK1）从各个峰面积计算的接合度评分，我们能够利用DNA信息正确表征样品中的杂合子和纯合子。然后将该分数用于表征没有DNA表征的样品的表观接合性。SPINK1的IC-LC-MS方法在0.5–1000μg/ L的浓度范围内是线性的。定量限（LOQ）为0.5μg/ L。IC-LC-MS和TR-IFMA分析显示出良好的相关性。平均接合度得分为1.00（95％CI为0.98–1.01，IC-LC-MS和TR-IFMA分析显示出良好的相关性。平均接合度得分为1.00（95％CI为0.98–1.01，IC-LC-MS和TR-IFMA分析显示出良好的相关性。平均接合度得分为1.00（95％CI为0.98–1.01， N34S  -SPINK1分别为wt，杂合和纯合的个体分别为n = 11），0.55（95％CI 0.43–0.61，n  = 14）和0.05（范围0.04–0.07，n = 3）。通过DNA分析获得变体。当DNA样品不可用时，该测定法也有助于鉴定档案血清样品中的N34S-和P55S-SPINK1变体。