Evaluation of a turbidimetric immunoassay for measurement of plasma IgG concentration in foals.

The research validates a method, called turbidimetric immunoassay (TIA), for measuring IgG plasma concentrations in newborn horses (foals). The study found that the TIA method quickly delivered verifiable results, making it a valuable tool for making time-sensitive clinical interventions.

Objective and Methodology

• The study aimed to ascertain the validity of a turbidimetric immunoassay (TIA) for quantifying plasma IgG concentrations in foals.
• 36 foals were used in this experiment. Blood samplings were conducted on the subjects before they were allowed to suckle and at intervals—12 hours and 24 to 36 hours—after birth.
• Commercial single radial immunodiffusion (RID) technique was employed for determining the concentrations of IgG in plasma.
• The researchers developed a TIA using a spectrophotometer and goat anti-equine IgG antiserum. This was done to measure concentrations of IgG in serum and plasma.
• Percentage light transmission was calibrated using RID assay-determined concentrations of IgG.
• The team analyzed the effects of serial dilution, type of sample, and ambient temperature on the TIA results, as well as the repeatability of the assay.

Key Results

• Results from the serial dilution of plasma samples taken from the foals at intervals showed a strong inverse correlation (r=-0.95) between percentage light transmission and the RID assay-determined IgG concentrations.
• The TIA measurements of IgG from plasma and serum samples were identical.
• The researchers observed that the coefficient of variation was less than 5% when the samples were assayed multiple times.
• Ambient temperature was found to have no influence on the TIA results.
• The TIA sensitivity surpassed 90% at IgG concentrations of 400 and 800 mg/dL. Specificity was recorded at 99.1% and 70.5%, respectively. Positive and negative predictive values were placed at 98.1% and 71.5%, and 96.4% and 91.1%, respectively.

Conclusions

• The study confirmed a high correlation between IgG plasma concentrations in foals calculated using TIA and RID assays.
• The TIA produced quantitative results quickly, making it a valuable diagnostic tool for use in time-critical clinical scenarios.