Are cytokine patterns in aqueous humour useful in distinguishing corneal graft rejection from opacification due to herpetic stromal keratitis?

Abstract

Intra-ocular cytokine profiles were determined to study the immunological mechanisms of corneal graft opacification due to rejection and/or herpetic stromal keratitis (HSK). Sera and aqueous humour (AH) were sampled shortly after the onset of corneal graft opacification, group I (n=18). In eyes with clear grafts, samples were taken 5 months after transplantation, group II (n=59). Samples of non-inflamed eyes, prior to cataract surgery, were used to determine baseline cytokine levels, group III (n=49). Total protein (TP) levels were measured with Bradford reagent and interleukin (IL)-6, IL-10, IL-4 and interferon (IFN)-gamma with ELISAs. All patients who's corneal grafts showed clinical evidence of graft opacification due to rejection and/or HSK were sampled. In the AH-samples of group I, increased levels of TP were found in 60% (9/15), IL-6 in 79% (11/14), IL-10 in 39% (7/18) and IL-4 in none (0/12). IFN-gamma was detected in 19% (3/16), in the case of HSK only. In contrast, samples obtained from patients with clear grafts in group II showed increased levels of TP in 36% (20/55), IL-6 in 14% (8/57) and IL-10, IL-4 or IFN-gamma in none (n=58). During corneal graft rejection and/or HSV-infection, increased levels of TP and IL-6 in AH confirmed anterior chamber inflammation with breakdown of the blood-aqueous barrier. Based on the data presented, cytokine patterns in the AH do not appear to distinguish corneal opacification due to graft rejection from that due to herpes keratitis.