Objective—To determine whether a chemokine
(RANTES)-like protein expressed by ciliary epithelium
plays a role in uveitis.
Sample Population—3 clinically normal horses intradermal,
5 eyes from 5 horses with recurrent uveitis,
and 10 normal eyes from 5 age- and sex-matched
Procedure—Cross-reactivity and sensitivity of recombinant
human (rh)-regulated upon activation, normal
T-cell expressed and secreted (RANTES) protein were
evaluated in horses by use of intradermal hypersensitivity
reactions and a chemotaxis assay. Aqueous
humor and ciliary body of eyes from clinically normal
horses and horses with uveitis were examined for
RANTES expression by use of an ELISA and reverse
transcription-polymerase chain reaction (RT-PCR).
Expression of RANTES mRNA and protein content of
primary cultures of equine ciliary pigmented epithelial
cells (RT-PCR) and culture supernatant (ELISA) were
measured 6 or 24 hours, respectively, after cultures
were stimulated with interleukin-1β and tumor necrosis
Results—Strong reactions to intradermal hypersensitivity
testing and significant chemotaxis of equine
leukocytes to rh-RANTES wereas observed. Aqueous
humor of eyes from horses with uveitis contained
increased concentrations of rh-RANTES-like protein
(mean ± SD, 45.9 ± 31.7 pg/ml), compared with aqueous
humor from clinically normal horses (0 pg/ml).
Ciliary body from horses with uveitis expressed
RANTES mRNA, whereas ciliary body from clinically
normal horses had low mRNA expression. Stimulated
ciliary pigmented epithelial cells expressed increased
amounts of rh-RANTES-like protein (506.1 ± 298.3
pg/ml) and mRNA, compared with unstimulated samples.
Conclusions and Clinical Relevance—Ciliary epithelium
may play a role in recruitment and activation of
leukocytes through expression of RANTES.
(Am J Vet Res 2002;63:942–947)