Occurrence of IgE in foals: evidence for transfer of maternal IgE by the colostrum and late onset of endogenous IgE production in the horse.

The study explores how IgE, an antibody necessary for Type I allergies, is transferred from mother horses to their offspring through colostrum. Researchers found that the IgE found in foals after birth comes from the mother and that foals start producing IgE independently at around 9-11 months of age.

Objectives and Methodology

• The primary objective of the study was to understand how the IgE antibody is transferred and later produced in foals. The researchers hypothesized that these antibodies come from the mother’s colostrum.
• To test their hypothesis, the researchers correlated the IgE concentration found in colostrum to the concentration of IgE in foal serum two days after birth. They employed ELISA, an enzyme-linked immunosorbent assay, to aid the detection of the IgE in the foal’s serum. They used flow cytometry to identify the presence of IgE on peripheral blood leukocytes, a type of white blood cell.

Findings

• The correlation between maternal colostrum’s IgE concentration and the total IgE in foal’s serum on the second day after birth was set at r(sp)=0.83, indicating a strong correlation.
• The measurements of serum and cell membrane-bound IgE hit peak values on days 2-5 after birth, suggesting that the source of these IgE antibodies is the colostrum ingested by the newborn foals. Neither serum nor cell membrane-bound IgE were detectable in newborns prior to colostrum consumption.
• By 2-4 months after birth, IgE in serum and those bound to cell membranes became undetectable. This indicates that the maternal IgE is eliminated from the foals’ systems within this period.
• Endogenous production of IgE (IgE produced by the foal itself) begins between 9-11 months of age. At this point, IgE was detectable again. When the foals are 18 months old, their total IgE concentration was similar to their mothers’ concentration.

Implications and Conclusions

• The late onset of endogenous IgE production in foals provides an explanation as to why allergies mediated by IgE are usually not observed in horses before they reach puberty.
• The roles of passively transferred maternal IgE in newborn foals are not clearly understood. However, the study suggests it could vary from providing passive immunity to influencing the offspring’s antibody repertoire and inducing immunoregulatory functions.