Peterson J A, Hamosh M, Scallan C D, Ceriani R L, Henderson T R, Mehta N R, Armand M, Hamosh P
Cancer Research Fund of Contra Costa, Walnut Creek, California 94596, USA.
Pediatr Res. 1998 Oct;44(4):499-506. doi: 10.1203/00006450-199810000-00006.
Human milk fat globule (HMFG) glycoproteins can prevent infections by microorganisms in breast-fed infants; the MUC-1 mucin inhibits binding of S-fimbriated Escherichia coli to buccal mucosa, and lactadherin may prevent symptomatic rotavirus infections. In this study, the survival of these HMFG glycoproteins in the stomach of human milk-fed preterm infants (gestational age = 27.5 +/- 0.4 wk) was assessed, and levels in their mothers' milk determined, using specific RIAs. Butyrophilin, a major component of HMFG membrane that has no demonstrated antimicrobial activity, was studied for comparison. The levels of mucin, lactadherin, and butyrophilin in 41 milk samples of 20 mothers were 729 +/- 75, 93 +/- 10, and 41 +/- 3 microg/mL, respectively. Mucin and lactadherin were significantly higher in early milk samples (<15 d postpartum) than in later milk samples (15-90 d postpartum), whereas butyrophilin showed no such difference. Significant amounts of mucin and lactadherin were found in almost all gastric aspirates of human milk-fed infants, even 4 h after feeding (mucin, 270 +/- 30 microg/mL; lactadherin, 23.2 +/- 4.4 microg/mL), whereas butyrophilin was rapidly degraded in the majority of aspirates. Western blot analysis demonstrated that the immunoreactive mucin, lactadherin, and butyrophilin in the milk-fed gastric aspirates had the expected native molecular weights. Mucin and lactadherin survived at all gastric pH values, whereas butyrophilin was found only at pH > 4. Neither lactadherin nor butyrophilin were detected in gastric aspirates of formula-fed infants (gestational age = 27.8 +/- 0.5 wk), whereas the very low level of mucin (9.1 +/- 1.1 microg/mL) in this group is presumably cross-reacting gastric mucin. These results demonstrate that two HMFG glycoproteins implicated in prevention of infection, MUC-1 mucin and lactadherin, survive and maintain their integrity in the stomachs of human milk-fed preterm infants.
人乳脂肪球（HMFG）糖蛋白可预防母乳喂养婴儿受到微生物感染；MUC-1粘蛋白可抑制S菌毛大肠杆菌与颊黏膜的结合，而乳黏附素可能预防有症状的轮状病毒感染。在本研究中，使用特异性放射免疫分析法评估了这些HMFG糖蛋白在母乳喂养的早产儿（胎龄 = 27.5±0.4周）胃内的存活情况，并测定了其母乳中的水平。为作比较，研究了乳脂肪球膜的主要成分嗜乳脂蛋白，其尚无已证实的抗菌活性。20位母亲的41份乳汁样本中，粘蛋白、乳黏附素和嗜乳脂蛋白的水平分别为729±75、93±10和41±3微克/毫升。初乳样本（产后<15天）中的粘蛋白和乳黏附素显著高于晚乳样本（产后15 - 90天），而嗜乳脂蛋白无此差异。在几乎所有母乳喂养婴儿的胃吸出物中都发现了大量的粘蛋白和乳黏附素，即使在喂食后4小时也是如此（粘蛋白，270±30微克/毫升；乳黏附素，23.2±4.4微克/毫升），而嗜乳脂蛋白在大多数吸出物中迅速降解。蛋白质印迹分析表明，母乳喂养的胃吸出物中具有免疫反应性的粘蛋白、乳黏附素和嗜乳脂蛋白具有预期的天然分子量。粘蛋白和乳黏附素在所有胃pH值下均能存活，而嗜乳脂蛋白仅在pH>4时被发现。在配方奶喂养的婴儿（胎龄 = 27.8±0.5周）的胃吸出物中未检测到乳黏附素和嗜乳脂蛋白，而该组中极低水平的粘蛋白（9.1±1.1微克/毫升）可能是交叉反应的胃粘蛋白。这些结果表明，两种与预防感染有关的HMFG糖蛋白，即MUC-1粘蛋白和乳黏附素，在母乳喂养的早产儿胃内能够存活并保持其完整性。
