Study: Saliva test shows promise in checking immunity status

Determining a patient’s immunity status may as simple as using an oral swab, according to a new study.

The report, titled, “The utility of saliva for the assessment of anti-pneumococcal antibodies: investigation of saliva as a marker of antibody status in serum,” published in the journal Biomarkers, revealed that saliva antibodies may serve as a non-invasive marker of systemic immunity status for certain vaccines that fight bacterial infections. Researchers assessed IgG, IgA and IgM antibody levels from saliva compared to those found in serum and found higher concentrations in saliva than in serum for IgG and IgA antibodies. Salivary IgM antibodies found in saliva, however, did not reveal protective status.

Some of the bacterial infections tied to these antibodies include Streptococcus pneumoniae (S. pneumoniae), which causes up to half of community acquired pneumonia (CAP) cases.

While serum studies have been the standard in assessing antibodies and protective status, assessment using saliva could be particularly useful in settings where resources are scarce.

“Saliva sampling may be able to help address the challenges of measuring antibodies in certain populations and settings and offer a potential biomarker of systemic immunity and vaccination; future studies in large populations are required to develop, optimize and validate further,” according to the report. “A non-invasive method of assessing protection against bacterial disease and vaccination responses could be particularly beneficial in countries introducing new vaccination programs/aiming to increase coverage. Saliva is an attractive method of specimen collection, particularly for children and the elderly, field research, or where repeated measures are required.”

Next: More research needed

More research needed

The use of saliva testing requires more validation before it can be used in clinical practice, but the potential is there, said Jennifer Heaney, a research fellow in clinical immunology at the Institute of Immunology and Immunotherapy at the College of Medical and Dental Sciences at the University of Birmingham in the United Kingdom and lead author of the study.

“This study increases understanding of the relationship between systemic and oral immunity.  Patients with protective antibody levels in serum are likely to have higher levels of antibodies in saliva. This research highlights the potential for salivary antibodies to identify antibody status in serum or as biomarkers of immune-competence,” Heaney told Medical Economics. “In the future, saliva testing may become part of a physician’s toolkit available to assess immunity. The present investigation focuses on pneumococcal antibodies but we have previously shown that it is possible to measure salivary antibodies against a range of bacterial antigens, including meningococcal and haemophilus polysaccharides and diphtheria and tetanus toxoids.”

In addition to being non-invasive, saliva sampling requires smaller volumes for study than serum and is not considered a class II biohazard so that collection can be done without special training and more cost-effectively than serum.

“The ability to measure anti-pneumococcal antibodies in saliva has several advantages compared to conventional serum testing, for both patients and healthcare practitioners. Patients may be more comfortable in providing a non-invasive and pain free saliva sample than a blood sample. Saliva requires no specialist training or equipment to collect making testing accessible in clinic and community settings,” Heaney said. “These considerations may result in more time and cost effective sample collection compared to phlebotomy. It may be particularly valuable in patients where venipuncture may be difficult, such as in children or the elderly, or when investigations require repeated sample measurements over time.”