title: Monozygotic twins are discordant for chronic periodontitis: white blood cell counts and cytokine production after ex vivo stimulation.
abstract: OBJECTIVE
  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.
  
  
  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)-1beta, IL-6, IL-8, IL-10 and IL-12p40 were assessed after stimulation of monocytic cells, while IL-13 and interferon (IFN)-gamma 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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Periodontology, Academic Center for Dentistry Amsterdam, University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: Gaudy L
authors.initials: GL
authors.lastname: Torres de Heens
authors.forename: Bruno G
authors.initials: BG
authors.lastname: Loos
authors.forename: Ubele
authors.initials: U
authors.lastname: van der Velden
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D055113:Chronic Periodontitis / Q000150:complications / Q000235:genetics / Q000276:immunology* / Q000473:pathology; D004200:Diseases in Twins / Q000276:immunology*; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D053762:Interleukin-12 Subunit p40 / Q000276:immunology*; D015850:Interleukin-6 / Q000276:immunology*; D007962:Leukocytes / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D017622:Periodontal Attachment Loss / Q000150:complications / Q000235:genetics / Q000276:immunology / Q000473:pathology; D012720:Severity of Illness Index; D014429:Twins, Dizygotic / Q000235:genetics / Q000276:immunology; D014430:Twins, Monozygotic / Q000235:genetics / Q000276:immunology
chemical_list: D053762:Interleukin-12 Subunit p40; D015850:Interleukin-6