Selected effects of kynurenine pathway components on the immune system. Numbers refer to the corresponding references which are listed in a separate section of the references list, but which are summarized as follows: F1: Badawy, 2017; F2: Badawy, 2018; F3: Fallarino et al., 2006; F4: Eleftheriadis et al., 2016; F5: Kirillova et al., 2008; F6: He et al., 2015; F7: Zhang et al., 2018; F8: Huang et al., 2017; F9: Bock et al., 2013; F10: Xie et al., 2015; F11: Pallotta et al., 2011; F12: Belladonna et al., 2006; F13: Orabona et al., 2012; F14: Albini et al., 2017; F15: Juhl et al., 2020; F16: Favre et al., 2010; F17: Porro et al., 2020; F18: Baban et al., 2009; F19: Mezrich et al., 2010; F20: Litzenburger et al., 2014; F21: Li et al., 2016; F22: Molano et al., 2008; F23: Harden et al., 2016; F24: Fallarino et al., 2002; F25: El-Zaatari et al., 2014; P26: Elizei et al., 2015; F27: Poormasjedi-Meibod et al., 2016; F28: Barth et al., 2009; F29: Kolodziej et al., 2011; F30: Wang et al., 2006; F31: Metghalchi et al., 2015; F32: Fallarini et al., 2010; F33: Malaczewska et al., 2016; F34: DiNatale et al., 2010; F35: Elizei et al., 2017; F36: Luchowski and Urbanska, 2007; F37: Lowe et al., 2014; F38: Giles et al., 2003; F39: Goldstein et al., 2000; F40: Okuda et al., 1998; F41: Chiarugi et al., 2001; F42: Guidetti and Schwarcz, 1999; F43: Hayashi et al., 2007; F44: Terness et al., 2002; F45: Lee et al., 2010; F46: Lee et al., 2013; F47: Pae et al., 2006; F48: Sekkai et al., 1997; F49: Lopez et al., 2008; F50: Lopez et al., 2006; F51: Hill et al., 2007; F52: Weber et al., 2006; F53: Varesio et al., 1990; F54: Bosco et al., 2004; F55: Pastorino et al., 2004; F56: Ladomersky et al., 2018; F57: Melillo et al., 1993; F58: Croitoru-Lamoury et al., 2003; F59: Guillemin et al., 2003; F60: Stone, 1993; F61: Stone and Perkins, 1981; F62: Hernandez-Martinez et al., 2017; F63: Kubicova et al., 2013; F64: Santamaria et al., 2001; F65: Perez-De La Cruz et al., 2012; F66: Guillemin, 2012; F67: Schwarcz et al., 2010; F68: Bhat et al., 2020; F69: Qin et al., 2000.