Saliva test could offer new way to check immunity

A saliva test may be a cost-effective and non-invasive tool to assess immunity of a person and help in vaccination against bacterial infections, particularly in developing countries, a new study has found.
Researchers from University of Birmingham in the UK have found that antibody levels in saliva are linked to those in blood serum, suggesting a new method for assessment of protection against bacterial infections.
In the study, samples of both blood and saliva were taken from 72 healthy adults. Samples were then analysed to test for concentrations of IgG, IgM and IgA antibodies against 12 pneumococcal (Pn) antigens.
The researchers found that in general, higher antibody concentrations in serum were associated with higher concentrations in saliva, with the strongest relationships observed for IgA antibodies.

While these preliminary results cannot yet be used to inform clinical decisions at an individual level, they suggest that measuring antibodies in saliva may have promise in future epidemiological studies relating to vaccination against bacterial infections, particularly in developing countries.
"Protection against bacterial infection is usually inferred by measuring antibody levels in blood serum," said Jennifer Heaney from University of Birmingham.

"But taking blood samples involves a number of logistical considerations and may not always be feasible, especially in developing countries or where children are involved. Saliva sampling is non-invasive, requires no specialist training or equipment, and may be more cost-effective.

"The suggestion that antibody levels in saliva may be indicative of those in serum therefore has important implications for markers of immunity and vaccination in many parts of the world," said Heaney.
"This research highlights the need for larger studies further to investigate the potential of saliva testing as a tool to assess immunity," she said.
Previous research from the University of Birmingham showed that lower levels of antibodies in saliva are associated with an elevated risk of mortality, and that saliva sampling to determine IgA secretion rate has the potential to be used as an indicator of overall health by professionals as part of a general check-up.

The study was published in the journal Biomarkers.