Transforming growth factor-β in human aqueous humor

The transforming growth factor-beta s are peptide growth factors known to play a central role in wound healing. Using a specific, in vitro assay of cell growth inhibition, we have detected transforming growth factor-beta (TGF-beta) in 24/24 aqueous humor specimens from eyes undergoing cataract extraction with intraocular lens implantation. The amount of TGF-beta ranged from 2.3 to 8.1 ng/ml (mean +/- SD = 4.5 +/- 1.7 ng/ml), with 61% present in the active form. Subtyping of TGF-beta was performed by addition of antibodies specific for the beta 1 and beta 2 isoforms to the growth inhibition assay, and confirmed with a sandwich enzyme-linked immunosorbent assay. None of the TGF-beta detected was of the beta 1 isoform; in contrast, the beta 2 isoform was present in every sample, implying that it might have originated from ocular tissues. The presence of this potent modulator of tissue repair in aqueous humor suggests a role in the healing processes following intraocular surgery, including glaucoma filtration surgery.