Testing Fibrinogen Degradation Products and Immunoglobulin A in Saliva of Vegetable Farm Workers

It is known that the effects of various environmental factors at agribusiness facilities cause body reactions of general and local adaptation, which in general reduces the threshold of organism tolerance. In some cases, adaptation reaction can go beyond physiological limits and manifest itself in various degrees of severity of inflammatory processes, which, in turn, can serve as a basis for pathology development

Commonly accepted indicators of such inflammation include acute-phase proteins which are minimal in the normal condition (or may be absent at all), while their level may increase tens and even hundreds of times under inflammation

A significant part of acute-phase proteins has been well studied and used in various studies quite actively; these are fibrinogen and its degradation products (FDPs), C-reactive protein (CRP), alpha-2-macroglobulin, alpha-1-antitrypsin, ceruloplasmin, complement components, lactoferrin, etc.

The vast number of acute-phase proteins is synthesized in the liver, immunocompetent cells, and glandular epithelium

Chronobiological analysis shows that various acute-phase components are released into the bloodstream in a certain sequence: FDPs, RNA, and serum-reactive protein (SRP) – from a few minutes to 3–5 hours; SRP, lactoferrin, etc. – from 6–8 to 24–72 hours; immunoglobulins – from 7 to 14 days. It becomes obvious that an increase in the level of acute-phase proteins in the blood can be regulated at different levels: transcription, translation, processing of protein precursors, and secretion of their cells

All this enriches researchers’ capabilities in their assessment of the status of health of various population segments, including agricultural production workers.

At the same time, non-traumatic and bloodless technologies of human examination with no loss in research quality and informativeness deserve all attention and support.

To assess acute-phase proteins in the saliva of agribusiness workers (workers of vegetable farm brigades), we chose fibrinogen and products of its degradation (FDPs) and immunoglobulin A out of several types of these proteins: the method of their detection in mixed saliva is the most developed, and according to literature sources, they are sufficiently indicative in various body states.

We examined 161 workers: all males, most of them (132) aged 20–40 years (82%).

117 male students of Astrakhan Medical University aged 19–25 years formed a control group.

Enrollment criteria included the absence of signs of diseases of the oral cavity, respiratory tract, gastrointestinal tract, as well as the absence of complaints and any diseases of internal organs in the medical history at the time of examination.

Workers’ saliva was sampled at their workplaces; the one of students – in classrooms. Saliva was sampled 2–3 hours after a meal or in the fasting state. Saliva samples were labeled and put in eppendorfs. The samples were transported to the laboratory in a chilled state (in refrigerated bags). To preserve the native protein structure, saliva was stored in refrigerators in the frozen state at temperatures from -8о to -10оС.

Before examination, all incoming saliva samples were exposed to demucination, threefold freezing and thawing of saliva with subsequent separation of precipitated mucoids by 30-minute centrifugation at 3,000 rpm. After centrifugation, saliva samples were preserved with sodium azide to a final concentration of 0.01–0.03% to prevent microbial growth.

Antisera of the Gamaleya National Center of Epidemiology and Microbiology were used for immunodiffusion analysis.

The statistical significance of differences in two related groups was calculated with a Student’s t-test. Microsoft Excel and Statistica for Windows were used for statistical analysis of the results.

3.1. Fibrinogen and its degradation products (FDPs) in the saliva of agribusiness workers

As acute-phase proteins, both fibrinogen and its degradation products are known to be uncommon components of saliva (i.e., they are absent in the normal condition). Therefore, in our study, they serve as indicators of a damaged microcirculatory barrier of the oral mucosa or salivary glands. Immunodiffusion analysis allowed to detect various FDP fragments in saliva in more than 27% of the study group – 44 out of 161 workers (Table 1).

As can be seen from Table 1, the number of workers with FDPs in saliva was more than 7 times higher than the frequency of their detection in healthy individuals of the control group.

The age and, to some extent, the length of service of the persons examined are among important indicators which are quite closely related to the general level of resistance and, consequently, morbidity. All the agriculture workers were divided into 3 rank groups by these characteristics:

– by age: up to 30 years old, 31–40 years old, and 41–60 years old;

– by length of service: up to 1 year, 1–3 years, 3–5 years and more.

Table 2 presents results of the comparisons made in this regard.

As is seen from Table 2, only a small, unreliable increase in the number of persons with FDPs was observed with an increment of the workers’ age. By the way, other authors also found no significant differences between age groups in various control groups where the age of the persons examined ranged from 20 to 50 years.

No reliable differences regarding the content of FDPs in workers of different service-length groups were noted, either. It is possible that this may be due to some stabilization of certain individuals with FDPs due to their body adaptation to etiological factors.

3.2. Serum immunoglobulin A in the saliva of agribusiness workers

Binding to microorganisms, immunoglobulin A antibodies inhibit their adhesion to the surface of epithelial cells and thus prevent their penetration into the internal environment of the organism.

The provided data indicate quite marked differences in the amount of immunoglobulin A in the saliva of workers and in the students’ saliva (p < 0,01).

The synthesis of acute-phase proteins in various lesions is quite a well-known fact, and it is actively used for diagnosis and treatment of human health disorders. As a rule, acute-phase proteins are studied in blood serum. At the same time, it is known that acute-phase proteins are found in other biological fluids, including mixed saliva, which is anatomically and functionally associated with other organs and systems of the organism, and, above all, with blood.

Our studies have shown that such acute-phase proteins as FDPs and immunoglobulin A can be used to assess body natural resistance along with other tests. Their common feature is that they were detected in vegetable farmworkers almost constantly. It seems to us that rather high levels of FDPs and immunoglobulin A, as fast-reacting acute-phase proteins, in the saliva of vegetable farmworkers may reflect different conditions in a living organism, from the activation of adaptation mechanisms of nonspecific defense to the premorbid state or already developed illness. In contrast to FDPs, an increase in the level of immunoglobulin A in saliva, as a slower component of defense, may reflect the presence of an already developed disorder in the organism.

Acute-phase proteins in vegetable farmworkers can be tested to identify initial or already formed signs of harmful effects of unfavorable production factors, along with other clinical, biochemical, hematologic, immunologic and other methods. In this regard, it seems reasonable to include a wider set of tests for acute-phase proteins of tissue and serum origin in order to reveal a more complete picture of the impact of adverse factors of the industrial environment on the human body.

It is also important to note that human saliva is a more convenient material for mass examination of people than blood serum due to non-traumatic, bloodless and quick material sampling, as well as relative epidemiological safety of methods of its sampling and analysis.