Halsey J F, Mitchell C, Meyer R, Cebra J J
Eur J Immunol. 1982 Feb;12(2):107-12. doi: 10.1002/eji.1830120203.
The metabolism of albumin and IgA was studied in normal and lactationg mice. Lactation resulted in significant changes in the metabolism of these proteins. The serum albumin concentration was lowered from 47 mg/ml in normals to 24 mg/ml in lactating mice. However, only a slight decrease in the serum concentration of IgA was observed during lactation. The proportion of polymeric and monomeric IgA in serum and milk was evaluated by gel exclusion chromatography. The onset of lactatin led to a rise in the proportion of polymeric IgA (P-IgA) in serum from 37% to 51%. The proportion of P-IgA in milk was 65% and remained constant throughout lactation. P-IgA and albumin were shown to be efficiently transferred from the serum of lactating mice into their milk. Serum decay studies were performed to evaluate the turnover of the serum pools during lactation. The rates of disappearance from the serum of isotopically labeled albumin and P-IgA were observed to increase dramatically during lactation, suggesting that both of these two mild proteins might be derived at least in part from the serum. The sites of synthesis of mild IgA (local vs. extra-mammary gland) were evaluated by determining the extent of dilution of isotopically labeled serum IgA during transport through the mammary gland into the milk. Early in lactation, the majority of the IgA in mouse milk appeared to be derived from distant sites and transferred via the blood to the mammary gland. However, by day 8 of lactation, the isotopically labeled P-IgA in milk was significantly diluted by the IgA synthesized in the mammary gland. Albumin and IgG were not diluted by local synthesis indicating that these proteins were exclusively serum-derived.
在正常小鼠和泌乳小鼠中研究了白蛋白和免疫球蛋白A（IgA）的代谢。泌乳导致这些蛋白质的代谢发生显著变化。血清白蛋白浓度从正常小鼠的47毫克/毫升降至泌乳小鼠的24毫克/毫升。然而，泌乳期间仅观察到血清IgA浓度略有下降。通过凝胶排阻色谱法评估血清和乳汁中聚合型和单体型IgA的比例。泌乳开始导致血清中聚合型IgA（P-IgA）的比例从37%升至51%。乳汁中P-IgA的比例为65%，且在整个泌乳期保持恒定。结果表明，P-IgA和白蛋白能有效地从泌乳小鼠的血清转移至乳汁中。进行血清衰变研究以评估泌乳期间血清池的周转率。观察到同位素标记的白蛋白和P-IgA从血清中的消失速率在泌乳期间显著增加，这表明这两种乳蛋白可能至少部分源自血清。通过测定同位素标记的血清IgA在通过乳腺转运至乳汁过程中的稀释程度，评估乳IgA（局部与乳腺外）的合成部位。泌乳早期，小鼠乳汁中的大多数IgA似乎源自远处部位，并通过血液转移至乳腺。然而，到泌乳第8天时，乳汁中同位素标记的P-IgA被乳腺合成的IgA显著稀释。白蛋白和免疫球蛋白G（IgG）未因局部合成而被稀释，这表明这些蛋白质完全源自血清。
