Active transforming growth factor-β2 is increased in the aqueous humor of keratoconus patients

Purpose: The secretion of transforming growth factor-beta(2) (TGF-beta(2)) into the aqueous humor was identified to be important for the maintenance of the immunological privilege in the anterior chamber of the eye. Therefore, prognosis of penetrating corneal grafts might depend on intraocular levels of TGF-beta(2). In this study, we determined active TGF-beta(2) levels in eyes with pathological corneas prior to penetrating keratoplasty (PK). Methods: Anterior chamber puncture was performed in 38 cataract patients without PK (group I), in 15 keratoconus eyes undergoing PK (group II), and in 66 eyes with various indications for PK (group III). About 0.05-0.1 ml of aqueous humor were harvested from each patient. Analysis of active TGF-beta(2) was started via ELISA within three h following puncture. Results: Average active TGF-beta(2) concentration was 39.9 +/- 24.3 pg/ml (median 41.1 pg/ml) in group I, 78.9 +/- 53.8 pg/ml (median 85.8 pg/ml) in group II, and 31.5 +/- 37.7 pg/ml (median 23.6 pg/ml) in group III. The differences between group II and groups I and III were statistically significant (p < 0.001). Conclusions: The highest levels of active TGF-beta(2) were found in keratoconus eyes. This finding might partly explain the excellent prognosis of keratoconus eyes regarding PK. Further (prospective) studies are being carried out to discover whether active TGF-beta(2) might serve as predictive parameter for immune reactions following PK.