Studies on the systemic availability of maternal and endogeneously produced immunoglobulin G1 and G2.

The time course of serum concentrations of the bovine IgG1 and IgG2 was monitored in 18 newborn colostrum-fed calves from birth to 11 weeks of age. All calves received three 1.5 l meals of a pooled colostrum with IgGl and IgG2 concentrations of 54.9 mg/ml and 4.2 mg/ml during the first 14 h post-natum. The mean IgG concentrations in calf serum increased from 0.15 mg IgG1/ml and 0.06 mg IgG2/ml (precolostral values) to 9.3 mg IgG1/ml and 0.8 mg IgG2/ml 12 h after the third colostrum meal. Thereafter, IgG1 decreased continuously to a minimum level of 4.9 mg/ml (p < 0.05) at day 28 post-natum and increased to 9.0 mg/ml at day 77. Postcolostral mean IgG2 was lowest (0.5 mg/ml) at day 11 and highest (1.2 mg/ml) at day 77. With these postcolostral IgG concentrations the respective body weight-corrected serum IgG pools approximately were calculated. According to that procedure the initially high IgG pool in the serum at day 2 corresponds to 11.3 and 8.7%, respectively, of the ingested colostral IgG1 and IgG2. The time course of these IgG pools in the serum could be characterized by four typical phases. After a rapid increase from 0.45 g to 22.6 g (12 h after the last colostrum meal) in phase I, the total serum IgG decreased to 17.6 g at day 11 post-natum (phase II) and levelled-out until day 28 post-natum at a value of 17.3 g (phase III). In phase IV total serum IgG increased to 49.3 g at the end of the observation period (week 11). Considering these IgG values, which had been standardized by body weight, the endogeneous IgG production seemed to start clearly (at week 1–2 post-natum) before the increase of the IgG concentration in the serum. To measure these IgG1 and IgG2 concentrations in the serum as well as in the colostrum, sandwich ELISA detection systems were developed which specifically quantify these IgG subclasses in cattle. The specific immunoglobulin Y (IgY) could be isolated from the egg yolk of laying hens which have been immunized with bovine IgG1... [ABSTRACT FROM AUTHOR]