Pneumococcal Immune Status Accurately Determined in Saliva Samples

Measurement of levels of antibodies against 12 Streptococcus pneumoniae antigens in saliva was shown to provide as accurate an indication of immune status against this organism as was determination of antibody levels in blood serum.

The objective of a study carried out at the University of Birmingham United Kingdom) was to assess if levels of anti-pneumococcal (Pn) antibodies in saliva reflected concentrations in serum and to determine whether saliva could accurately identify protective concentrations in serum.

Toward this end the investigators employed a multiplex assay, the BioRad Laboratories (Hercules, CA, USA) Luminex-200, Bioplex System, that simultaneously measured antibody concentrations against 12 Pn antigens, to determine IgG, IgA, and IgM antibody levels in paired saliva and serum samples against 12 Pn polysaccharide antigens in 72 healthy adults.

Results revealed that antibody levels in saliva correlated positively with serum across immunoglobulin classes, most strongly for IgA. Individuals who had protective antibody levels in serum demonstrated significantly higher IgG and IgA salivary antibody concentrations and secretion rates. Salivary IgG and IgA Pn antibodies were able to distinguish between those with/without protective levels in serum for the majority of serotypes. Salivary IgM antibodies were not able to differentiate protective status.

First author Dr. Jennifer Heaney, a researcher in immunity and infection at the University of Birmingham, said, "Protection against bacterial infection is usually inferred by measuring antibody levels in blood serum. 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. This research highlights the need for larger studies further to investigate the potential of saliva testing as a tool to assess immunity."

The study was published in the December 12, 2016, online edition of the journal Biomarkers.

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University of Birmingham
BioRad Laboratories