title: Production and turnover of IgG1 and IgG2 immunoglobulins in the bovine around parturition.
abstract: Production rates (entry rate into blood plasma) and other metabolic parameters for the IgG1 and IgG2 subclasses of immunoglobulins in mammary secretions (ratio of about 7 to 1) were determined in cows around the time of parturition by both single-injection and continuous-infusion isotope-dilution techniques. Four cows were given a single dose of 150 to 200 muCi of iodine-125 labeled IgG1 and 100 to 250 muCi of iodine-131 labeled IgG2 at 2 to 1 wk before parturition. Four cows, including two of the above, were infused continuously with constant amounts of the labeled immunoglobulins starting at 11 to 4 days before parturition. All cows were maintained until 4 to 6 days after parturition for monitoring the specific activities of iodine-125 labeled IgG1 and iodine-131 labeled IgG2 in the plasma and mammary secretions. Maximum entry rates of IgG1 and IgG2 were between 3 and 1 day prepartum with means of 125 and 60 g/500 kg body weight per day. The exchangeable pool means for IgG1 and IgG2 were 619 and 643 g/500 kg body weight, and both immunoglobulins were divided almost equally between the intra- and extravascular pools. A greatly increased production and a shortened half-life or greater turnover for plasma IgG1 occurs around the time of parturition which can account for the large accumulation of IgG1 in colostrum.
mesh_terms: D000818:Animals; D002417:Cattle / Q000276:immunology* / Q000502:physiology; D003126:Colostrum / Q000276:immunology; D005260:Female; D007074:Immunoglobulin G / Q000378:metabolism* / Q000652:urine; D007743:Labor, Obstetric; D008321:Mammary Glands, Animal / Q000276:immunology; D010953:Plasma Volume; D011247:Pregnancy
chemical_list: D007074:Immunoglobulin G