*4.3.1. The α-globulins*

The α fraction is the most rapidly migrating protein of all the globulins, and in most species, it migrates as α<sup>1</sup> (fast) and an α<sup>2</sup> (slow) fraction. Many diagnostically important acute-phase proteins migrate in this fraction. Alpha<sup>1</sup> -antitrypsin, α<sup>1</sup> -acid glycoprotein, α<sup>1</sup> -antichymotrypsin, α1 -fetoprotein, serum amyloid A, and α<sup>1</sup> -lipoprotein have been identified in the α<sup>1</sup> -globulin fraction, while haptoglobin, α<sup>2</sup> -microglobulin, α<sup>2</sup> -macroglobulin, ceruloplasmin, α<sup>2</sup> -antiplasmin and α<sup>2</sup> -lipoprotein in the α<sup>2</sup> -globulin fraction [100, 133]. Acute-phase proteins are a large and varied group of serum proteins, with numerous differences in their concentrations between different animal species [134]. Their concentrations change in response to any alterations in homeostasis or tissue injury. They have specific functions in the regulation of inflammatory processes, predominantly at the site of inflammatory lesions, but they may act also systemically [115]. In general, the main function of the acute-phase proteins is to defend the host against pathological damage, remove the causative agents of disturbances, assist in the restoration of the homeostasis and in the regulation of different stages of inflammation [135, 136]. Moreover, some proteins from these fractions may act as inhibitors of enzymes, as digest proteins, as compounds of the blood coagulation system or as carrier of copper [71].

## *4.3.1.1. Alpha-1 antitrypsin*

concentrations between different animal species [126]. Albumin can be seen on the left side

Albumin is small size protein with a molecular weight of 69 kDa. The main functions of albumin are the maintenance of homeostasis and transportation of substances, and it also acts as a free-radical scavenger [127]. It is responsible for about 75% of the osmotic pressure of plasma and is a major source of amino acids that can be utilized by the animal's body when necessary [128]. It also serves as a carrier protein for many insoluble organic substances (e.g., unconjugated bilirubin). Serum albumin is the major negative acute-phase protein. The synthesis of positive acute-phase proteins is markedly increased during the acute inflammatory processes. These reactions require a great amount of amino acids. Thus, albumin synthesis is downregulated and amino acids are used mainly for the synthesis of the positive acute-phase proteins [129]. Catabolism of albumin occurs in various tissues, where it enters cells by pinocytosis and is then degraded by proteases [130]. The major sites of these catabolic processes are muscle, liver, and kidney. There are major species-specific differences in the turnover of albumin, reflecting the body size. The half-time for clearance of albumin varies from 1.9 days in the mouse to 14–16 days in ruminants, and because of this, it may serve as a marker of chronic nutritional status [131]. Furthermore, may studies have established albumin as an indicator of

The globulin fractions may be found on the right side of the electrophoretogram. These peaks include a very heterogenous group of proteins, and depending on the species, there may nor-

The α fraction is the most rapidly migrating protein of all the globulins, and in most species, it

varied group of serum proteins, with numerous differences in their concentrations between different animal species [134]. Their concentrations change in response to any alterations in homeostasis or tissue injury. They have specific functions in the regulation of inflammatory processes, predominantly at the site of inflammatory lesions, but they may act also systemically [115]. In general, the main function of the acute-phase proteins is to defend the host against pathological damage, remove the causative agents of disturbances, assist in the restoration of the homeostasis and in the regulation of different stages of inflammation [135, 136]. Moreover, some proteins from these fractions may act as inhibitors of enzymes, as digest

proteins, as compounds of the blood coagulation system or as carrier of copper [71].



(slow) fraction. Many diagnostically important acute-phase pro-








mally be one or two α, one or two β, and one or two γ fractions [22].

of the electrophoretogram closest to the anode, where forms a large peak [76].

morbidity and mortality [132].

114 Ruminants - The Husbandry, Economic and Health Aspects

(fast) and an α<sup>2</sup>


teins migrate in this fraction. Alpha<sup>1</sup>

fraction, while haptoglobin, α<sup>2</sup>


**4.3. Globulins**

*4.3.1. The α-globulins*

migrates as α<sup>1</sup>

α1

and α<sup>2</sup>

Alpha-1 antitrypsin (AAT) is the major inhibitor of serine proteases (serpin) such as neutrophil elastase and proteinase-3 in the blood [137]. It is also an acute-phase protein. In some acute-phase inflammatory reactions, the concentrations of AAT may increase in order to limit the damage caused by activated neutrophil granulocytes and their enzyme elastase, thus limiting the tissue injury caused by proteases at the site of inflammation [138]. The clinical importance of AAT is underlined in patient with AAT deficiency, a hereditary disorder that can lead to severe tissue breakdown during inflammation [139]. Consequently, pulmonary emphysema, chronic obstructive lung disease, liver diseases, as well as liver cirrhosis may occur in these patients. In addition, liver cells produce an abnormal protein, which may accumulate in the body, leading to inflammation and/or cirrhosis of the liver [140]. From animal species, Sevelius et al. [141] measured the concentrations of alpha-1 antitrypsin in dogs and evaluated whether AAT aggregates could initiate liver disease. In cattle, little is known about the diagnostic utility of alpha-1 antitrypsin.

#### *4.3.1.2. Alpha-1 acid glycoprotein*

Alpha-1 acid glycoprotein (AGP) or orosomucoid is a highly glycosylated protein of which about 45% is carbohydrate and the composition of the glycan residues is known to alter during an acute-phase response [142]. AGP is considered as a natural anti-inflammatory and immunomodulatory agent. It has also been suggested that AGP is required to maintain capillary permeability [142]. Furthermore, AGP is one of the most important drug-binding proteins in plasma that can have important pharmacokinetic implications [143]. It has a moderate acute-phase response in most animal species and is more likely associated with chronic conditions. The serum concentration of AGP may be a valuable differential diagnostic analyte in the identification of feline infectious peritonitis [144].

In ruminant species, the concentrations of AGP were evaluated by Tóthová et al. [145] in calves during the first month of life. In this study, the AGP values were roughly uniform shortly after birth with an increase of values from the day 2 of life till the end of the first month of age, probably related to the normal process of growth, exposure of animals to changing environmental conditions, and nutritional factors. Similar findings were demonstrated by Rocha et al. [146]. On the other hand, the highest concentrations of AGP in the plasma were found by Itoh et al. [147] in calves immediately after birth (1368 μg/ml), gradually decreasing to 249 ± 100 μg/ml during the first 3 days of life, which are comparable to physiological values in adult bovine. Similarly, high plasma concentrations of AGP were observed by Orro et al. [148] in calves after birth, which was followed by a decrease during the first 3 weeks of life to adult values. The very high concentrations of AGP in the fetal stages may be related to synthesis of AGP in the embryonic liver [147]. These studies indicate that the production of AGP in the neonatal period is fetally regulated and its high serum concentrations after birth are not necessarily a sign of the activation of the acutephase response by external stimuli.

#### *4.3.1.3. Alpha1 -fetoprotein*

Alpha<sup>1</sup> -fetoprotein (AFP) is the predominant serum protein in the bovine fetus, which is mainly produced by the yolk sac and at the later period by the fetal liver [149]. Because of its biochemical similarity to albumin, AFP could be a carrier protein, or even take part in the metabolism of bilirubin [150, 151].

Eckersall et al. [168] found significantly elevated SAA concentrations in sheep with experimental caseous lymphadenitis induced by *Corynebacterium pseudotuberculosis*. Chalmeh et al. [169] observed in sheep, a rapid increase of SAA values during experimentally induced endotoxaemia by lipopolysaccharide from *Escherichia coli*. Another study conducted by El-Deeb [170] showed an increase in the concentrations of SAA in ewes with pregnancy toxemia. Marked increase of SAA concentrations was recorded also in sheep following experimental infestation with *Psoroptes ovis* [171]. After treatment, the SAA values decreased rapidly within 3 days and returned to the pre-infestation values for 10–14 days. The alterations in the acute-phase protein production during experimental caprine coccidiosis were evaluated by Hashemnia et al. [172]. They found markedly higher concentrations of SAA at day 7 after inoculation. Furthermore, the magnitude and duration of the acute-phase responses are cor-

The Use of Serum Proteins in the Laboratory Diagnosis of Health Disorders in Ruminants

http://dx.doi.org/10.5772/intechopen.72154

117

Haptoglobin (Hp) is a glycoprotein that consists of two α and two β chains, connected by disulfide bridges [173]. In the circulation, Hp is highly polymerized, having a molecular weight of approximately 1000–2000 kDa, and exists also as a polymer associated with albumin [174]. The primary function of Hp is to bind free hemoglobin released from erythrocytes and thereby inhibits its oxidative activity [175]. The Hp-hemoglobin binding also reduces the

Many studies have indicated the significance of Hp as a clinically useful parameter for measuring the occurrence and severity of inflammatory responses in cattle with various diseases, including mastitis, enteritis, peritonitis, pneumonia, as well as endocarditis [136, 177]. Higher concentrations of Hp were found also by Sheldon et al. [178] in cows with uterine bacterial contamination. In addition, Hp was detected in ewes as prognostic indicator of ovine dystocia [179]. Gonzalez et al. [180] studied the possible use of acute-phase proteins as markers of subacute ruminal acidosis in goats. They found a moderate increase of Hp concentrations during the induction period, while SAA did not change. In a further study, Gonzalez et al. [181] determined the effect of fasting-induced pregnancy toxemia on the concentrations of acute-phase proteins in goats. They found a significant increase only in the concentrations of Hp, but not in other acutephase proteins. The changes of some inflammatory markers were evaluated also in goats around kidding [182]. Their results suggest that an increase of inflammatory indicators (mainly Hp) before kidding may be related to the changes in the energy balance status around parturition.

Ceruloplasmin (Cp) is a ferroxidase enzyme that is the major copper-carrying protein in the blood, and plays a role in iron metabolism [183]. Ceruloplasmin carries 70–95% of the total copper in plasma, and thus might play a role in Cu and iron homeostasis [184]. Furthermore, ceruloplasmin is involved in cellular prooxidant and antioxidant processes, and has antibacterial activities [185]. It is produced by the liver as apoceruloplasmin, an unstable non-copper-bound form, which subsequently reacts with seven copper atoms forming holoceruloplasmin, a func-

related well with the severity of the clinical signs and diarrhea in goat kids.

availability of the heme residue from bacterial growth [176].

*4.3.1.5. Haptoglobin*

*4.3.1.6. Ceruloplasmin*

tional and more stable product [186].

Smith et al. [152] have demonstrated that the concentrations of AFP in fetal bovine plasma reach the highest values in the 3–4th of fetal period, which is followed by significant decrease until birth. A decrease of the values of AFP in the first hours of life was obtained by Bader et al. [149] that may represent the physiological effect on the fetal tissues changing from an intrauterine to an extrauterine environment, with decrease in the production of fetal proteins in the liver. Lee et al. [153] concluded that following the initial decrease of the values of AFP within hours after birth, the concentrations of AFP tend to stabilize during the rest of the first week, and then decrease rapidly. On the other hand, Tóthová et al. [122] found a marked increase of AFP concentrations 1 day after colostrum intake, with following gradual decrease of values up to day 30 of life. The relatively higher values of AFP after birth may be associated with its synthesis (not ceasing entirely at birth) by fetal hepatocytes that continue during the early postnatal period [154]. Furthermore, colostrum contains many non-nutrient substances and immune factors, including alpha<sup>1</sup> -fetoprotein, which may be responsible for the increased concentrations of AFP in calves 1 day after colostrum intake [155].

Alpha<sup>1</sup> -fetoprotein may be used as a tumor marker to help detect and diagnose cancers of the liver, testicles, and ovaries. Sturgeon et al. [156] reported increased concentrations of AFP in approximately 70% of patients with hepatocellular carcinoma. Increased AFP concentrations were found also in 50–70% of patients with nonseminomatous testicular tumors. In veterinary medicine, the possible use of AFP as disease marker was not yet evaluated.
