Determination of leucocyte subsets in human saliva by flow cytometry

Abstract Objective Validation of a flow cytometry-based method for the determination of major leucocyte subsets [polymorphonuclear (PMN) cells, monocytes, T cells and B cells] in paraffin-stimulated whole human saliva. Design Salivary leucocyte subsets were determined by four-colour flow cytometry in eight healthy volunteers on three consecutive days. Comparison of leucocyte subsets between saliva and whole blood was also performed. Day-to-day variability and intraclass correlation coefficients (ICC) were determined as indicators of assay reliability. Results It was observed that PMN cells were the predominant cells in the saliva. Percentages of mononuclear cells ranged from 0.3% to 7.2%, with monocytes composing the highest percentage, followed by T cells and B cells. Regardless of high intra-individual day-to-day variability, proportions of leucocyte subsets did not significantly change over three measurements, and high ICCs were calculated for T cells and monocytes. Conclusion Flow cytometry can be used as non-invasive and reproducible method for the analysis of leucocyte subsets in human saliva. Further investigation of pathological and other conditions that have the potential to influence salivary leucocyte subsets is warranted.