Monozygotic twins are discordant for chronic periodontitis: white blood cells counts and cytokine production after ex vivo stimulation

Objectives: The aim of this study was to investigate the extent of concordance in the number of leucocytes and their cytokine secretion after ex vivo stimulation in a twin population discordant for the amount of periodontal breakdown.
Material and Methods: Venous blood was collected from 18 adult twin pairs (10 monozygotic and eight dizygotic twins). Each twin pair consisted of a diseased twin (proband) and his/her co-twin. In venous blood, leucocytes were counted. The cytokines interleukin (IL)-1β, IL-6, IL-8, IL-10 and IL-12p40 were assessed after stimulation of monocytic cells, while IL-13 and interferon (IFN)-γ were determined after lymphocytic stimulation.
Results: In the study population as a whole, probands showed higher total numbers of leucocytes and lower IL-12p40 levels compared with their co-twins. In monozygotic twins, no difference was found in the leucocyte counts, but probands secreted more IL-6 than their co-twins; an opposite trend was found for IL-12p40.
Conclusion: The results suggest that the observed discordance in periodontal breakdown in the studied monozygotic twin population may be related to the relatively high levels of IL-6 and the low levels of IL-12p40 secretion after ex vivo stimulation of whole-blood cell cultures. This cytokine secretion profile may be regarded as a risk indicator of periodontitis.