Cytokines have been defined as regulatory proteins produced by immune cells and other cells of the body. Their pleiotropic action includes numerous effects on the cells of the immune system and modula- tion of inflammatory responses. The im- mune system, through cytokine- and interleukin-mediated pathways can regu- late the reproductive system by inducing the release of gonadotropins, such as luteinizing hormone and follicle-stimulat- ing hormone. It seems that communication between the endocrine and immune sys- tems determines the expression of inter- leukins in puberty (19). In an effort to elucidate possible mechanisms of age- associated changes in immunity, the impact of age on cytokine production has been examined in humans. However, studies examining alterations in proinflam- matory cytokine production with age are contradictory: both an increase and/or no change have been reported between differ- ent age groups (9, 21, 25, 26). The analysis of cytokine production levels has been also used as a tool for studying the local host response to a bacterial challenge. In particular, a large number of cytokines present in the gin- gival crevicular fluid (GCF) have been proposed as potentially useful diagnostic or prognostic markers of periodontal destruction (3, 11). Among these, inter- leukin-1b (IL- 1b), IL-4, and IL-8 have been shown to function in concert with other members of the cytokine network to regulate the cellular inflammatory response in the periodontium. In all these studies, it is important, however, to acknowledge the variation of cytokines with age. The present cross-sectional study was designed to determine the levels of IL-1b, IL-4, and IL-8, in the GCF of healthy adolescents and young adults. Oral Microbiology Immunology 2009: 24: 7–10 Printed in Singapore. All rights reserved Ó 2009 The Authors. Journal compilation Ó 2009 Blackwell Munksgaard Cytokines in gingival crevicular fluid of adolescents and young adults Kamma J, Mombelli A, Tsinidou K, Vasdekis V, Giannopoulou C. Cytokines in gingival crevicular fluid of adolescents and young adults. Oral Microbiol Immunol 2009: 24: 7–10. Ó 2009 The Authors. Journal compilation. Ó 2009 Blackwell Munksgaard. Background/aim: The purpose of this study was to compare the levels of the cytokines interleukin-1b (IL-1b), IL-4, and IL-8 in the gingival crevicular fluid (GCF) of adolescents and young adults. Methods: Twenty-five adolescents aged between 14 and 16 years (Group A) and 20 periodontally healthy young adults aged between 25 and 35 years (Group B) were selected from two private dental clinics limited to pedodontics and periodontics respectively in Piraeus Greece. All subjects were systemically healthy. Clinical examination included probing pocket depth (PPD), presence or absence of plaque, and bleeding on probing (BOP). GCF was collected from four sites per subject. IL-1b, IL-4, and IL-8, measured as total amounts (pg/30 s), were evaluated in 180 samples using a commercially available sandwich enzyme-linked immunosorbent assay. Results: IL-1b mean levels of Groups A and B were adjusted for BOP and PPD. Differences of IL-1b mean levels between the two age groups were statistically significant (F = 50.245, P < 0.001) in favour of Group A. Adolescents showed statistically significantly lower mean levels of IL-4 than young adults in the presence of BOP (F = 10.690, P = 0.001). There was no statistically significant difference between adolescents and adults for the means of IL-8 adjusted for BOP and plaque presence (F = 2.032, P = 0.161). Conclusions: Within the limits of this study the differences reported in mean levels of IL-1b and IL-4 may be attributed to the different age status. J. Kamma 1 , A. Mombelli 2 , K. Tsinidou 3 , V. Vasdekis 4 , C. Giannopoulou 2 1 Private Dental Clinic limited to Periodontics, Piraeus, Greece, 2 Department of Periodontol- ogy, University of Geneva, Geneva, Switzer- land, 3 Private Dental Clinic limited to Pedodontics, Piraeus, Greece, 4 Athens Uni- versity of Economics and Business, Greece Key words: age; cytokines; gingival crevic- ular fluid Joanna Kamma, 6-8 Freattidos st., GR- 185 37 Piraeus, Greece Tel.: +30 210 4525 935; fax: +30 210 4525 935; e-mail: joannakamma@gmail.com Accepted for publication June 12, 2008