Biology of Sport, Vol. 30 No4, 2013 243 Salivary IL-21 and IgA responses to a competitive match in elite basketball players ”eprint request to: Alexandre Moreira University of São Paulo School of Physical Education and Sport Av. Prof Mello de Moraes, 65 São Paulo - SP - Brazil 05508-030 E-mail: alemoreira@usp.br Accepted for publication 07.04.2013 INTRODUCTION It has been demonstrated that athletes engaged in strenuous training might have an increased risk of infection because of transient immune suppression [6,19]. Probably, an insuficient period of recovery be- tween successive training sessions may cause suppression of the immune system [2], increasing the risk of illness (e.g. greater inci- dence of upper respiratory tract infections – U”TI). Furthermore, additional psychological stress could also affect the immune response of individuals [4]. In immunosuppressed athletes the mucosal surfaces are potential targets for pathogenic agents given their interface with the external environment. Such surfaces are normally protected by a network of organized structures located in the gut, urogenital tract, oral cavity and respiratory system, collectively known as the mucosal immune system (MIS) [9]. A low level of immunoglobulin A (IgA), particu- larly salivary IgA (sIgA), the major effector of the MIS [2], is associ- ated with increased risk of U”TI in athletes [6, 7]. Moreover, transient falls in sIgA are also related to increased risk of U”TI [17]. The sIgA responses to acute exercise have been investigated dur- ing distinct designs, modes of exercise and sports. The results are SALIVARY IL-21 AND IGA RESPONSES TO A COMPETITIVE MATCH IN ELITE BASKETBALL PLAYERS AUTHORS: Moreira A. 1 , Bacurau R.F.P. 2 , Napimoga M.H. 3 , Arruda A.F.S. 1 , Freitas C.G. 1 , Drago G. 4 , Aoki M.S. 2 1 School of Physical Education and Sport, University of Sao Paulo, Sao Paulo, Brazil 2 School of Arts, Sciences and Humanities, University of Sao Paulo, Sao Paulo, Brazil 3 São Leopoldo Mandic Institute and Research Center, Campinas, Sao Paulo, Brazil 4 Pinheiros Sport Club, Sao Paulo, Brazil ABSTRACT: Athletes engaged in strenuous training might experience transient immune suppression that could lead to greater incidence of upper respiratory tract infections (URTI). Since interleukin 21 (IL-21) stimulates immunoglobulin A (IgA) secreting cells and a low level of this immunoglobulin is associated with increased incidence of URTI, the aim of the present study was to investigate the effect of a basketball match on salivary cortisol (sC), salivary IL-21 (sIL-21) and salivary IgA (sIgA) levels. Twenty male basketball players participated in an oficial game in two teams (10 players in each team). The saliva samples were collected before the warm- up and approximately 10-15 min after the end of the match and were analysed by ELISA methods. sC concentration increased signiicantly after the match while sIL-21 level was reduced (p < 0.05). In opposition to the study’s hypothesis, sIgA level did not change in response to the match. The present indings suggest that a basketball match is suficiently stressful to elevate sC concentration and attenuates the sIL-21 output without compromising the sIgA level. It is reasonable to speculate that the stability of sIgA acute responses to the match, despite the decrement in sIL-21, indicates that other mechanisms rather than IL-21 stimulating B cell proliferation/differentiation might modulate IgA concentration and secretion rate. KEY WORDS: mucosal immunity, saliva, stress, interleukin, immunoglobulin still somewhat inconclusive and have produced conlicting indings. sIgA concentration is unchanged after moderate aerobic exercise lasting less than 1 h [2] as well as after a 70-minute soccer match [13]. On the other hand, some studies have reported decreased sIgA level following endurance sports such as swimming [27], kay- aking [12], running [18] or in response to two futsal games in profes- sional players [14]. A limitation to understanding the sIgA responses is that the po- tential mechanisms by which exercise inluences salivary responses are poorly investigated. ”ecently, it has been shown that sIgA secret- ing cells are stimulated by interleukin (IL)-21, a potent inducer of human B cell proliferation/differentiation [11, 21, 24] which is pro- duced by CD4+ T cells (especially T helper 17 (Th17)-producing cells) and natural killer T (NKT) cell [23]. Interestingly, IL-21 rap- idly induced the generation of immunoglobulin-secreting cells and the secretion of vast quantities of sIgA from B cell subsets, and its effect exceeded that of IL-10 by up to 100-fold, highlighting the potency of IL-21 as a B cell differentiation factor [3]. Despite the well-established stimulatory role of IL-21 on sIgA secreting cells, Original Paper Biol. Sport 2013;30:243-247 DOI: 10.5604/20831862.1077548 - - - - - Electronic PDF security powered by www.IndexCopernicus.com