HPLC‐ESI‐MS analysis of oral human fluids reveals that gingival crevicular fluid is the main source of oral thymosins β 4 and β 10

Thymosin β 4 (Tβ 4 ), its sulfoxide, and thymosin β 10 (Tβ 10 ) were detected in human saliva and identified by different strategies based on RP HPLC coupled to electrospray multidimensional IT MS. Tβ 4 was almost always detected in whole saliva, its sulfoxide sporadically, Tβ 10 rarely. Tβ 4 was undetectable in parotid saliva and less concentrated in submandibular/sublingual saliva than in whole saliva. Analysis of gingival crevicular fluid revealed high relative amounts of Tβ 4 , Tβ 4 sulfoxide, and Tβ 10 in all the samples. Tβ 4 mean concentration was 200 times higher in crevicular fluid (20 μmol/L, N = 9) than in whole saliva (0.1 μmol/L, N = 9). Crevicular fluid concentration of Tβ 4 ( ca . 5% represented by its sulfoxide) and β 10 significantly correlated ( r = 0.856; N = 9), and their ratio was about 5. A significant correlation was also observed between Tβ 4 concentrations in whole saliva and gingival crevicular fluid ( r = 0.738; N = 9). Immunohistochemical analysis of the major salivary glands showed that immunoreactivity for Tβ 4 is restricted to ductal cells, with minor degree of focal positivity in some acinar cells. On the whole, results indicate that gingival sulcus is a main, although not the sole, source for oral Tβ 4 and Tβ 10 .