Aldridge B M, McGuirk S M, Lunn D P
Department of Medical Sciences, School of Veterinary Medicine, University of Wisconsin, Madison 53706, USA.
Vet Immunol Immunopathol. 1998 Mar 18;62(1):51-64. doi: 10.1016/s0165-2427(97)00158-x.
The importance of colostrum for passive transfer of maternal immunoglobulin in calves is well established. Colostrum is thought to have additional generalized and antigen-specific immunomodulatory activities, of which the downregulation of endogenous immunoglobulin production is best documented. The objective of this study was to examine whether ingestion of colostrum altered the B cell subpopulations in the lymph nodes of newborn calves. Calves were fed one gallon of either fresh colostrum (Group A, n = 5), milk replacer (Group B, n = 5) or treated (frozen or irradiated) colostrum (Group D, n = 4) and were euthanized at 36-48 h. An additional 5 calves (Group C, 3 newborn and 2 mid-term fetuses) did not receive any feedings; the neonatal calves were euthanized immediately following birth. Mesenteric and regional lymph nodes from all calves were analyzed by immunocytochemistry using monoclonal antibodies recognizing bovine IgA, IgG1, IgG2, and IgM. Calves from Groups B and C (colostrum deprived, neonates, and fetuses) showed a consistent pattern of IgG1 and IgG2 positive cells scattered individually and in clusters throughout lymph node cortex, paracortex, and cortico-medullary junction. In sharp contrast, no IgG1 and IgG2 positive cells were present in the lymphoid tissues of colostrum fed calves (Groups A or D). Numbers of IgM and IgA positive cells were similarly distributed in all calf groups. These findings demonstrate that colostrum feeding reduces the number of immunoglobulin positive cells in the lymphoid tissues of newborn calves in an isotype-specific manner. This results in the elimination of IgG1 and IgG2 positive cells that are present in both fetuses and newborn calves. This effect is not eliminated by freezing or irradiation, indicating that a non-cellular, cold-stable colostral factor is responsible. Systemically distributed colostral proteins such as immunoglobulin or cytokines are the most likely mediators. The significance of this phenomenon in terms of colostral modulation of calf endogenous antibody production is discussed.
初乳对于犊牛母体免疫球蛋白被动转移的重要性已得到充分证实。初乳被认为具有额外的全身性和抗原特异性免疫调节活性，其中内源性免疫球蛋白产生的下调有最充分的文献记载。本研究的目的是检验摄入初乳是否会改变新生犊牛淋巴结中的B细胞亚群。给犊牛喂食1加仑新鲜初乳（A组，n = 5）、代乳品（B组，n = 5）或经处理（冷冻或辐照）的初乳（D组，n = 4），并在36 - 48小时后实施安乐死。另外5头犊牛（C组，3头新生犊牛和2头中期胎儿）未接受任何喂食；新生犊牛出生后立即实施安乐死。使用识别牛IgA、IgG1、IgG2和IgM的单克隆抗体，通过免疫细胞化学方法分析所有犊牛的肠系膜淋巴结和局部淋巴结。B组和C组（初乳剥夺组、新生犊牛和胎儿）的犊牛显示出一致的模式，IgG1和IgG2阳性细胞单个或成簇地分散在整个淋巴结皮质、副皮质和皮质 - 髓质交界处。形成鲜明对比的是，喂食初乳的犊牛（A组或D组）的淋巴组织中不存在IgG1和IgG2阳性细胞。IgM和IgA阳性细胞的数量在所有犊牛组中分布相似。这些发现表明，喂食初乳以同型特异性方式减少了新生犊牛淋巴组织中免疫球蛋白阳性细胞的数量。这导致消除了胎儿和新生犊牛中都存在的IgG1和IgG2阳性细胞。冷冻或辐照不会消除这种效应，表明一种非细胞、冷稳定的初乳因子起作用。全身分布的初乳蛋白如免疫球蛋白或细胞因子最有可能是介质。讨论了这种现象在初乳对犊牛内源性抗体产生的调节方面的意义。
