|Year : 2015 | Volume
| Issue : 2 | Page : 203-206
Age-related changes of salivary IgA among healthy subjects
Sayeda Fatima Khan1, Girish Katti2, Irfan Baba2, Naved Khan3
1 Department of Oral Medicine and Radiology, Rungta College of Dental Sciences and Research, Bhilai, Chhattisgarh, India
2 Department of Oral Medicine and Radiology, Al Badar Dental College and Hospital, Gulbarga, Karnataka, India
3 Department of Oral and Maxillofacial Surgery, Government Dental College, Raipur, Chhattisgarh, India
|Date of Submission||27-Aug-2014|
|Date of Acceptance||18-Oct-2015|
|Date of Web Publication||21-Nov-2015|
Sayeda Fatima Khan
Department of Oral Medicine and Radiology, Rungta College of Dental Sciences and Research, Kohka-Kurud Road, Bhilai, Chhattisgarh
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Introduction: The major immunoglobulin present in mucosal secretions (e.g. saliva) is secretory immunoglobulin A (IgA). The potential functions of this secretory IgA include prevention of microbial attachment to surfaces by agglutination, blockage of receptor-mediated attachment, and altering surface hydrophobicity. IgA in saliva is detected early in life as the mucosal immune system develops and the oral cavity is exposed to microbes that make up the normal ecology, as well as to potential pathogens. Lower concentration of IgA in saliva is associated with increased risk for periodontal disease and caries. The secretory IgA is the first line of defense against pathogens that invade the mucosal surfaces. The immune system exhibits profound changes with age and this fact has been well documented. Aims and Objectives: To investigate and re-confirm that salivary IgA concentration undergoes changes with advancing age, and further, to find if there is any probable difference in salivary IgA levels between men and women. Materials and Methods: Saliva samples were taken from 120 healthy subjects aged 1-60 years who were divided into the following age groups: 1-10 years, 11-20 years, 21-30 years, 31-40 years, 41-50 years, and 51-60 years. The salivary IgA concentrations were measured by use of single radial immune diffusion technique and analyzed using the paired and unpaired Student's t-test, and coefficient test as appropriate, and P values of less than 0.5 were considered significant. Results: The mean salivary IgA levels showed significant changes in each decade of the subjects selected. The mean salivary IgA levels were significantly higher in adults than those observed in children. Conclusion: These results showed that the salivary IgA levels exhibit age-related changes.
Keywords: Adult, child, immunoglobulin A, saliva, single radial immune diffusion technique
|How to cite this article:|
Khan SF, Katti G, Baba I, Khan N. Age-related changes of salivary IgA among healthy subjects. J Indian Acad Oral Med Radiol 2015;27:203-6
|How to cite this URL:|
Khan SF, Katti G, Baba I, Khan N. Age-related changes of salivary IgA among healthy subjects. J Indian Acad Oral Med Radiol [serial online] 2015 [cited 2019 Dec 6];27:203-6. Available from: http://www.jiaomr.in/text.asp?2015/27/2/203/170138
| Introduction|| |
Saliva is commonly referred to as bloodstream of the oral cavity and has a major role in maintaining teeth enamel mineralization.  Saliva plays an important role in defense against pathogenic microorganisms due to the presence of defense proteins that react in specific (immunoglobulins) or non-specific (lysozyme, peroxidase, cystatins, lactoferrin, histatins) ways inhibiting the growth of micro-organisms.  Immunoglobulins are glycoprotein molecules that are produced by plasma cells in response to an immunogen and function as antibodies. Out of all immunoglobulins, salivary immunoglobulin A (IgA) is the first line of defense against pathogens that invade the mucosal surfaces. The salivary IgA antibodies help maintain the integrity of the oral surfaces by preventing microbial adherence to epithelial and tooth surfaces by neutralizing enzymes, toxins, and viruses or by acting in synergy with other antibacterial factors. Salivary IgA also prevents the penetration of food antigens in the oral mucosa. Lower concentration of IgA in saliva is associated with increased risk for periodontal disease and caries. ,
It is well documented that all the components of the immune system get reconditioned with age, which further leads to increased or decreased functions related to them. However, it has been shown that mucosal immunization is an effective method in increasing the IgA levels in mucosal secretions.  Accordingly, it may be possible to induce salivary IgA response via oral immunization, when the salivary IgA concentrations begin to decrease during one's lifetime. This strategy could help the maintenance of the salivary IgA levels and improve oral immunity.  This study was conducted to evaluate age-dependent changes of salivary IgA levels in healthy subjects aged 1-60 years who were categorized into age groups of 1-10 years, 11-20 years, 21-30 years, 31-40 years, 41-50 years, and 51-60 years. This subject has not been extensively studied, hence the study was undertaken to throw more light on this aspect.
| Materials and Methods|| |
The number of subjects selected for the study was 120 in the age group between 1 and 60 years. Only healthy subjects were included in the study, and subjects suspected of having low immunity with a history of asthma, allergies, repeated infections, chronic illness, and deleterious habits were excluded. Children were selected from various schools, orphanages, and community health centers. The non-teaching staff and undergraduate students of our institute were explained about the study and they were selected as the adult group. For the older age group (>50 years), subjects were selected from old age homes and among relatives or grandparents of the earlier selected adult group. The subjects were divided into six age groups with equal male to female ratio in each group. The enlisted subjects were registered and an individual registration number was given to every subject. Before the commencement of the study, each subject, and parents/guardians in case of children were well informed about the study and written consent was obtained from them. Later, the saliva samples were collected according to their registration numbers.
Collection of saliva
The subjects were instructed not to take any food or drinks after getting up in the morning and collection of saliva was done between 10 and 11 am. No salivating agent was administered and the subjects were asked to naturally generate saliva in their mouths and spit into sterilized wide containers repeatedly over the duration of 5 min. The collected saliva samples were kept in an ice bath momentarily and then transferred to a centrifugal machine for 15 min at 1000 g to separate impurities. The samples were stored in a deep freezer at −70°C to be used later.
IgA quantification in saliva
The quantitative estimation of IgA was done by single radial immune diffusion technique (SRID). Three milliliters of buffered 1% agar was used to produce a 1.5-mm-thick gel. The required volume of saliva was pipetted out into a universal container and placed in a water bath. Fifty milligrams of measured agar and 10 ml of Tris-Tricine buffer were added and heated with frequent shaking till the solution became transparent. Five milliliters of molten agarose mixture was poured on a clean glass plate. The gel was allowed to set and then equilibrate in a moist chamber at 4°C. Origin wells for loading the test and standard solutions were prepared with a gel cutter.
Measured volumes of test and standard solutions were loaded into the origin well. The loaded gel was placed in a moist chamber at room temperature until completion of diffusion. The precipitin formed in the agar was in the form of a ring. Finally, the gel was placed in 1% tannic acid for 5 min to enhance the precipitin ring. The ring diameter (d) was measured to the nearest 0.1 mm. A standard graph was prepared using the WHO immunoglobulin standard. 
Paired and unpaired Student's t-test and coefficient test were used to analyze the variables, and P values of less than 0.5 were considered significant.
| Results|| |
Salivary IgA levels
The results of our study showed the followed values: group 1 (1-10 years), 5.20 ± 0.94 mg/dl; group 2 (11-20 years), 7.47 ± 1.48 mg/dl; group 3 (21-30 years), 8.17 ± 1.38 mg/dl; group 4 (31-40 years), 8.65 ± 1.17 mg/dl; group 5 (41-50 years), 9.79 ± 1.63 mg/dl; and group 6 (51-60 years), 10.21 ± 0.92 mg/dl [Table 1] and Graph 1]. The levels were in near approximation with those in the previous study done by Jafarzadeh et al.  Although the differences were not statistically significant, women were found to have higher mean salivary IgA levels than men. However, the salivary IgA levels were found to be considerably higher in adults than in children. This shows correlation between age and IgA levels which was statistically significant (P < 0.01).
| Discussion|| |
The immune system exhibits profound age-related changes. IgA constitutes the predominant immunoglobulin isotype in secretions of human saliva. Salivary IgA is the first warrior of body's defense mechanism against the invasion of pathogens on any mucosal surface. It prevents infections by inhibiting the adherence of pathogens to epithelial and tooth surfaces. It is well documented that with higher concentration of IgA in saliva, the incidence of dental caries was found to significantly reduced, whereas lower IgA concentration in saliva is proportional to increased risk of dental caries, periodontal diseases, and upper respiratory tract infections. 
In the present study, we observed that the differences in the levels of salivary immunoglobulins between men and women were not significant. The total mean value was 8.22 ± 1.21 in men and 8.27 ± 0.97 in women. This was found to be similar to the findings of Eliasson et al.  It has been observed in some studies that the IgA levels were significantly higher in women than in men without any known cause. We, therefore, suggest further studies on the salivary secretion and the hormonal pattern affecting the salivary secretions in men and women to find out the difference in salivary IgA levels between them. However, we observed that the changes in salivary IgA level with sex were not related to age, as this difference was found in all age groups, and also, in our study, the ratio of men and women was equal in all age groups.
A study done by Jafarzade et al. showed a slight drop in salivary IgA levels after 60 years of age.  However, our study was conducted on subjects only till the sixth decade of life. This decline in the salivary IgA levels after the age of 60 years could be attributed to the higher risk of oral infections in the elderly. , Eliasson et al.  investigated IgA concentrations in secretions of palatal, buccal, and labial salivary glands in individuals aged 18-72 years. The saliva samples of individuals beyond the age of 65 have shown to have higher salivary IgA levels than other individuals. Increased whole salivary IgA concentrations in older ages have been attributed partly to positive age-related effects on IgA concentrations in the buccal gland secretions.
It has also been reported that secretion of salivary IgA is higher in children of age 1-12 years.  Childers et al.  determined the concentrations of IgA in the parotid saliva of healthy children (age 6-12 years, n = 14) and healthy adults (age 22-51 years, n = 20) and reported that the levels of IgA increased with age. Researchers have also reported that the salivary IgA was found to be at the maximum in oldest studied individuals (>80 years). , However, genetic and environmental differences and differences in oral health may account for the differences in results obtained in this study and those reported by other investigators. 
| Conclusion|| |
The results of this study make it more evident that salivary IgA levels undergo changes with advancing age. Hence, the study results encourage conducting further studies to elucidate the precise cellular and molecular mechanisms responsible for these changes, in order to improve oral immunity.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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