Smith W D, Wells P W, Burrells C, Dawson A M
Clin Exp Immunol. 1976 Mar;23(3):544-53.
Concentrations of IgG, IgM and IgA were measured in the serum, nasal secretions and lachrymal secretions of suckled newborn lambs. The major immunoglobulin constituent of precolostral serum was IgM. Maternal immunoglobulins, of which IgG was predominant, reached peak values on day 1 of life and then declined over the next 3 weeks. Half lives were calculated as: IgG, 13-7 days; IgM, 4-1 days; and IgA 1-8 days. No immunoglobulin was detectable in nasal or lachrymal secretions prior to sucking but IgG was present in all samples of these secretions obtained approximately 24 hr after first sucking. IgG was present in nasal washings from suckled lambs, reared either naturally or on immunoglobulin-free milk substitute and levels declined as the lambs grew older. IgM and IgA did not appear consistently in the secretions until lambs were 2-3 weeks old. It was concluded, therefore, that colostral IgG reaches the nasal and lachrymal secretions of the newborn lamb. However, because the ewes in this experiment had only low serum titres, no maternal antibody to parainfluenza 3 virus (PI3) was detected in the nasal secretions of the lambs, although non-specific inhibitors were present. It is suggested, however, that low levels of maternal antibody in the secretions may play a valuable role in preventing respiratory virus infections of young ruminants before active local production of IgA and IgM begins at 2 to 3 weeks of age.
对哺乳新生羔羊的血清、鼻分泌物和泪液分泌物中的IgG、IgM和IgA浓度进行了测量。初乳前血清中的主要免疫球蛋白成分是IgM。以IgG为主的母体免疫球蛋白在出生第1天达到峰值，然后在接下来的3周内下降。半衰期计算如下：IgG为13 - 7天；IgM为4 - 1天；IgA为1 - 8天。在吮乳前，鼻分泌物或泪液分泌物中未检测到免疫球蛋白，但在首次吮乳后约24小时获得的这些分泌物的所有样本中均存在IgG。在自然饲养或以无免疫球蛋白的代乳品饲养的哺乳羔羊的鼻洗液中存在IgG，且随着羔羊年龄的增长，其水平下降。直到羔羊2 - 3周龄时，IgM和IgA才始终出现在分泌物中。因此得出结论，初乳中的IgG可到达新生羔羊的鼻分泌物和泪液分泌物中。然而，由于本实验中的母羊血清滴度较低，尽管存在非特异性抑制剂，但在羔羊的鼻分泌物中未检测到针对副流感3病毒（PI3）的母体抗体。然而，有人提出，在2至3周龄开始活跃地局部产生IgA和IgM之前，分泌物中低水平的母体抗体可能在预防幼龄反刍动物呼吸道病毒感染方面发挥重要作用。
