In-Vitro Evaluation of Ocular Irritants Using Tissue Isoelectric-Focusing Protein Profiles from Human, Rabbit, and Bovine Corneal Specimens

Tissue isoelectric focusing (TIF) was used to establish a reference bovine corneal protein profile and to compare the human, rabbit, and bovine corneal response to in vitro chemical exposure. TIF provided a direct, semiquantitative comparison of tissue-irritant interactions without the potential limitations of standard homogenization and extraction procedures. The in vitro exposure of corneal sections to acetic acid (2%) and ammonium hydroxide (1%) solutions resulted in selective modifications of tissue protein profiles, which were evaluated by scanning densitometry. Comparison of the human and rabbit corneal protein changes associated with in vitro chemical exposure revealed a similar acid/base effect on a common rabbit and human corneal protein band (pI = 8.1). The pI = 8.1 protein band did not occur in the bovine protein profile; however, a similar acid/base effect occurred with a protein band having a pI = 7.2.