Concentrations of passively acquired IgG1 antibodies in the intestinal lumen of the neonatal calf.
Passively acquired specific antibodies in the intestinal lumen are thought to provide protective immunity against infections with rotaviruses and other enteropathogens. In this study, concentrations of functional antibody in the intestinal lumen derived from diet and circulation were measured using 2,4-dinitrophenol (DNP) specific antibody of the IgG1 isotype, radiolabelled with 125I. The labelled IgG1 antibody was administered to neonatal calves either orally in the daily milk diet for three consecutive days (Group 1), or by a single intravenous injection (Group 2). After equilibration, the concentrations of protein-bound 125I and the specific DNP binding activities of the labelled protein in the intestinal lumen were measured, and intestinal concentrations of functional IgG1 were estimated. In Group 1 calves, protein bound 125I concentrations in the pooled small intestinal contents at 2 and 12 h after a milk meal were 50.8 +/- 20.5% and 7.9 +/- 3.4%, respectively, of the milk concentration. Protein bound 125I concentrations in the small intestinal contents were 0.7 +/- 0.4% (mean +/- SD) of serum concentrations of Group 2 calves, and were similar at 2 and 12 h after a milk meal. For a calf with average serum passive IgG1 concentrations drinking milk with normal IgG1 content, these results predict IgG1 concentrations in the small intestinal contents of milk fed calves at 2 h after a milk meal to be 0.6 mg ml-1, half of which originates from the milk and half from the circulation. At 12 h after a milk meal, intestinal IgG1 concentrations fall to approximately 0.3 mg ml-1, most of which originates from the circulation. Antibody in the intestinal lumen originating from serum retained more antigen (DNP) binding affinity than that ingested in the milk diet. Therefore, both dietary and circulating IgG1 contribute significantly to passive IgG1 antibody concentrations in the small intestinal lumen of neonatal calves, but milk derived IgG1 antibody concentrations in the small intestinal lumen were not maintained between twice daily feedings.
Besser
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Department of Veterinary Microbiology and Pathology, Washington State University, Pullman 99164-7040.
D000018:Abomasum / Q000276:immunology; D000818:Animals; D000831:Animals, Newborn; D002417:Cattle / Q000276:immunology*; D004140:Dinitrophenols / Q000276:immunology; D007116:Immunization, Passive; D007074:Immunoglobulin G / Q000032:analysis*; D007422:Intestines; D008297:Male; D008892:Milk / Q000276:immunology; D012709:Serum Albumin / Q000276:immunology
D004140:Dinitrophenols; D007074:Immunoglobulin G; D012709:Serum Albumin