Experimental ocular onchocerciasis in cynomolgus monkeys.

Infection of cynomolgus monkeys with microfilariae (Mf) of Onchocerca lienalis was studied as a model for human ocular onchocerciasis. Normal monkeys and immunized monkeys were given intracorneal/subconjunctival, intracameral, or intravitreal injections of Mf or bovine serum albumin (control). Selected animals were given diethylcarbamazine citrate (DEC) orally (15 mg/kg) daily after the ocular infection. Following intravitreal challenge, living Mf and fibrinous exudates were visible by slit-lamp in both the anterior chamber and vitreous. Eosinophils and macrophages surrounded the Mf in the vitreous, with degranulated eosinophils adherent to the Mf. Eosinophils infiltrated the uvea and surrounded the retinal vessels. After intracorneal injection of Mf, living Mf were visible by slit-lamp biomicroscopy in the cornea for 3 days, with minimal inflammation of the corneas occurring over the 7 days after injection. Intracamerally injected Mf induced anterior uveitis. The extent of the inflammatory reactions was not substantially altered by DEC treatment following intraocular injection of Mf. In vitro proliferative responses of peripheral blood leukocytes to a crude Mf antigen were not observed in infected monkeys and proliferative responses to mitogen declined in these animals. Responses to mitogen were inhibited by addition of Mf antigen in vitro in normal monkeys. Circulating IgG antibodies were present in the sensitized, intracorneally, and intravitreally challenged animals. No obvious correlations were present between IgG antibody level and ocular inflammation.