Do salivary antibodies reliably reflect both mucosal and systemic immunity?

Area of Science:

• Immunology
• Oral Biology
• Mucosal Immunity

Background:

• Saliva contains two major antibody classes: secretory IgA (SIgA) and IgG.
• SIgA is synthesized locally in salivary glands, while most salivary IgG originates from serum.
• The immune inductive sites for mucosal antibody production, such as gut-associated lymphoid tissue (GALT) and nasopharynx-associated lymphoid tissue (NALT), have differential contributions to salivary antibody responses.

Purpose of the Study:

• To investigate the distinct origins and regulation of secretory IgA (SIgA) and IgG in saliva.
• To examine the relationship between systemic and mucosal immune responses and salivary antibody levels.
• To highlight the complexities and potentials of saliva as a diagnostic fluid.

Main Methods:

• Analysis of antibody classes (SIgA and IgG) in saliva.
• Comparison of salivary antibody responses with immune induction in GALT and NALT.
• Evaluation of factors influencing antibody levels in oral secretions, including assay standardization and sample handling.

Main Results:

• Enteric immunostimulation is an inadequate method for stimulating salivary IgA antibodies.
• The IgA response in submandibular/sublingual glands is more closely related to GALT B cell induction than the parotid response.
• Salivary IgA levels can be altered in conditions like AIDS and celiac disease, with specific patterns observed in different salivary glands.

Conclusions:

• Salivary SIgA responses are not consistently associated with intestinal SIgA, suggesting distinct immune induction sites.
• Parotid SIgA may be more linked to immune induction in the palatine tonsils and adenoids (human NALT).
• Despite challenges in standardization and potential confounding factors, saliva holds significant scientific and clinical potential for immunological studies.