Volume 56 (2006) Issue: 2006 No#2-3

Fratrić Natalija, Jovčić-Milošević Nadežda, Ilić Vesna, Stojić V

Author(s): The levels of immune complexes in the blood sera of calves in the neonatal period and in adult cattle

Keywords:immune complexes, IgG, calves, PEG assay

In this work immune complexes (IC) in the sera of healthy calves from birth to four months of age, heifers and cows were investigated. Polyethylen glycol (PEG) precipitation assay was applied after previous standardization. Optical density (OD) of redissolved precipitates, formed after adding PEG to serum samples, was a measure of IC level. The upper-limit values for normal IC levels were established using isolated cattle IgG in different amounts and aggregated by heat as an IC model in vitro, in the same assay. In newborn calves before colostrum intake, OD of 0.047±0.024 was registered in redissolved PEG precipitates, far below the values obtained for native, monomeric IgG. Therefore, these values can not be considered to refer to immune complexes. After colostrum intake, OD values for normal IC levels were higher, with significant interindividual differences: in calves at 6, 24 and 48 hours after birth the mean OD values of solubilized PEG precipitates were 0.069±0.025, 0.148±0.079, and 0.136±0.062 respectively. In the sera of calves 10 days after birth mean OD value was slightly lower, 0.089±0.053, whereas in the serum of 1, 2, 3 and 4 month old calves normal levels of IC rose to 0.165±0.067, 0.157±0.080, 0,231±0,124 and 0.261±0.092 respectively. OD values for IC levels for adult animals were found to be 0,456±0,150 for heifers, and 0,183±0,031 for cows. Together, the obtained data may be included in a reference values system for normal levels of IC at different ages, in relation to which the IC levels under pathological conditions could be estimated.