Calvert I S, Weintraub B D, Panton L, Gaffney L, Rosen S W
Am J Obstet Gynecol. 1985 May 1;152(1):103-11. doi: 10.1016/s0002-9378(85)80190-3.
Macromolecular forms of human placental lactogen have received little attention because it has been thought that such forms either compose only a small fraction of total immunoactive placental lactogen or are merely laboratory artifacts. We examined serum and placental tissue from women with normal pregnancy (first and third trimesters), serum and tissue from women with eutopic tumors (mole and choriocarcinoma), and serum from men with ectopic placental lactogen production. Samples were chromatographed on dextran gel (Sephadex G-100), and placental lactogen was measured in the fractions by radioimmunoassay. In all specimens examined, immunoactive placental lactogen was found at the void volume of the column (molecular weight greater than 150,000 daltons). This macromolecular placental lactogen comprised less than 4% of total placental lactogen in the third trimester, in mole, and in 16 of 18 first-trimester samples but was significantly higher, up to 19%, in the malignant cases. In two first-trimester placental extracts (but not in their matched sera) macromolecular placental lactogen was the dominant (greater than 45% of the total placental lactogen) immunoactive species. Authentic monomeric placental lactogen was not converted to macromolecular placental lactogen by repeated freezing and thawing. Third-trimester placental macromolecular placental lactogen was unstable; only 13% remained at the void on rechromatography. First-trimester placental macromolecular placental lactogen, on the other hand, was stable to rechromatography. The behavior of immunochemical dilutions of macromolecular placental lactogen from first-trimester placenta was similar to that of monomeric placental lactogen in the same sample. Macromolecular placental lactogen is probably not artifact, and it can comprise a large fraction of the total immunoactive placental lactogen in certain conditions.
人胎盘催乳素的大分子形式很少受到关注，因为人们一直认为这些形式要么仅占总免疫活性胎盘催乳素的一小部分，要么仅仅是实验室假象。我们检测了正常妊娠女性（孕早期和孕晚期）的血清和胎盘组织、患有良性肿瘤（葡萄胎和绒毛膜癌）女性的血清和组织，以及产生异位胎盘催乳素男性的血清。将样本在葡聚糖凝胶（葡聚糖G - 100）上进行层析，并通过放射免疫测定法测定各组分中的胎盘催乳素。在所有检测的标本中，免疫活性胎盘催乳素在柱的空体积处被发现（分子量大于150,000道尔顿）。这种大分子胎盘催乳素在孕晚期、葡萄胎以及18个孕早期样本中的16个中占总胎盘催乳素的比例不到4%，但在恶性病例中显著更高，可达19%。在两份孕早期胎盘提取物中（但在其匹配的血清中未发现），大分子胎盘催乳素是主要的（占总胎盘催乳素的45%以上）免疫活性种类。通过反复冻融，纯单体胎盘催乳素不会转化为大分子胎盘催乳素。孕晚期胎盘大分子胎盘催乳素不稳定；重新层析时只有13%保留在空体积处。另一方面，孕早期胎盘大分子胎盘催乳素对重新层析是稳定的。孕早期胎盘大分子胎盘催乳素免疫化学稀释物的行为与同一样本中单体胎盘催乳素的行为相似。大分子胎盘催乳素可能不是假象，并且在某些情况下它可以占总免疫活性胎盘催乳素的很大一部分。
