Structural and functional properties of immune complexes in calves with bronchopneumonia

Abstract

Bronchopneumonia is the most frequent cause of calves’ ailments around the world. The absence of adequate immune response to causative agents of bronchopneumonia in calves remained unclear to date. The infectious agents of virus and/or bacterium origin associated with bronchopneumonia are omnipresent harmless commensals in the cattle population that induce illness when the host defense is depressed by environmental stress factors and inability of calves to fully respond to an antigenic stimulus due to the fragile nature of the immune system. The disease is a leading cause of economic loss in the livestock industry worldwide which points to the necessity of attending to this problem with great attention. Having in mind that immune response to certain pathogens responsible for bronchopneumonia in calves is IgG antibody-dependent, the presence of immune complexes containing these antibodies could have an important role in the pathogenesis of bronchopneumonia. The goal of this doctoral dissertation was to investigate the protein and lipid components of circulating immune complexes (CIC) of calves three months old, diagnosed with bronchopneumonia caused by Pasteurella multocida bacterium, and their role as modulators of immune response. CIC were isolated by polyethylene glycol precipitation. The level of polyethylene glycol precipitating CIC in calves with bronchopneumonia compared to healthy calves was higher. In calves with bronchopneumonia CIC were larger in size. CIC were composed of five groups of corpuscles; In healthy calves the most abundant corpuscles in CIC were of 1426±291 nm in diameter; In healthy calves corpuscles with hydrodynamic radius of 225±33 nm and 734±174 nm were mostly present in CIC. In calves with bronchopneumonia zeta potential of CIC was slightly higher than zeta potential of CIC in healthy calves. In calves with bronchopneumonia increased level of serum total proteins was detected. The concentration of γ and α globulins in the serum and in CIC of diseased calves was higher. The concentration of IgG and transferrin in the sera was higher, but remained unchanged in CIC of diseased calves...

Bronhopneumonija je najčešće oboljenje teladi u svetu ali do danas nije razjašnjeno zašto imunski sistem teladi ne odgovara efikasno na uzročnike bronhopneumonije. Virusi i bakterije uzročnici bronhopnemonije su komensali i izazivaju bolest samo kada je imunološka odbrana slaba, koja kod teladi nastaje zbog nezrelosti imunskog sistema i izloženosti stresu uzrokovanom nepovoljnim vremenskim prilikama i smeštajem u slabo ventilirane, prenaseljene i vlažne objekte. Kako je ovo oboljenje uzrok velikih ekonomskih gubitaka na govedarskim farmama postoji velika potreba da se problem ovog oboljenja reši. Imajući u vidu da je imunitet teleta na neke od uzročnika bronhopneumonije posredovan IgG antitelima i da bi imunokompleksi koje ova antitela formiraju mogli da učestvuju u patogenezi bronhopneumonije, ova doktorska disertacija je za cilj imala ispitivanje proteinskih i lipidnih komponenti cirkulišućih imunokompleksa (CIC) teladi starih tri meseca, obolelih od bronhopneumonije izazvane bakterijom Pasteurella multocida, najčešćim uzročnikom bolesti na farmama u okolini Beograda, i ispitivanje uloge CIC kao modulatora funkcija ćelija imunskog odgovora. U ovoj doktorskoj disertaciji CIC su izolovani precipitacijom proteina krvnog seruma polietilen glikolom. Nivo CIC teladi sa bronhopneumonijom je u odnosu na zdravu telad bio povećan. CIC teladi sa bronpneumonijom su bili veći. U CIC obe grupe teladi na osnovu hidrodinamičkog radijusa izdvaja se pet grupa čestica; u CIC bolesne teladi najzastupljenije su bile čestice od 1426±291 nm; a u CIC zdrave teladi čestice hidrodinamičkog radijusa od 225±33 nm i 734±174 nm. Zeta potencijal CIC teladi sa bronhopneumonijom je bio neznatno veći od zeta potencijala CIC zdrave teladi. U serumima teladi sa bronhopneumonijom detektovan je povišen nivo ukupnih proteina...