Technical Notes: Assay Precision Impact of Salivary Cytokine Contamination

Mask Worn No Mask Worn
Figure 1, Mask Worn Figure 1, No Mask Worn
Figure 1. The plate on the left was run by an operator wearing a mask, while the plate on the right was run by an operator without a mask and talking while running the assay (note: both plates were run with the same mid-level standard).

A number of studies have documented the presence of endogenous levels of cytokines and related molecules within saliva.1-3 When an analyte is present within an operator’s saliva, coughing, sneezing, or even speaking while running an ELISA can affect the overall results. For example, cytokines derived from saliva may impact assay precision. As a result, it is important to take the necessary precautions to prevent saliva-borne analyte contamination of the plate.

R&D Systems' Quantikine® ELISA development team routinely screens saliva samples during the assay development process. During the development process for the Quantikine human CCL28 ELISA, the potential effects of cytokine contamination from operator saliva on assay performance was assessed (see figure 1). These results underscore the importance of taking the necessary precautions to prevent salivary cytokine contamination when running these ELISAs.

Levels of Additional Analytes Found in Saliva
Analyte Mean (pg/mL) Range (pg/mL)
IL-8 817 122 - 1,590
IP-10 729 292 - 1,340
MMP-7 14,700 3,800 - 28,300
MMP-9 201,000 102,000 - 543,000
PDGF-AA 353 86 - 745
TIMP-1 121,000 46,000 - 208,000
TIMP-2 16,000 10,000 - 22,000
sVEGF R1 280 119 - 577
CCL28 47,846 21,900 - 68,200
Table 1. These and many other human kits detect significant levels of their respective analytes in saliva.


  1. Winkler, O. et al. (2001) Int. J. Hyg. Environ. Health 204:181.
  2. Al-Harthi, L. et al. (2000) J. Interferon Cytokine Res. 20:719.
  3. Fujioka, N. et al. (1995) J. Interferon Cytokine Res. 15:719.