Polymorphonuclear leukocyte infiltration into the subretinal choroid and optic nerve in response to leukotrienes

To describe the pattern of leukocyte infiltration in ocular anterior and posterior segment tissues in response to local administration of LTB4 and LTD4.

Leukocyte infiltration after intravitreal administration of LTB4 or LTD4 was assessed in ocular sagittal cross-sections and compared with vehicle-treated control eyes.

A dose-dependent eosinophil infiltration was observed in the subretinal choroid and the ora serrata region of the ciliary body in response to both LTB4 and LTD4, but only LTB4 behaved as a chemoattractant for neutrophils. Subretinal eosinophils achieved Bruch's membrane in response to LTB4 but, though gathered in several foci, this important barrier was not breached and leukocytes did not reach the neural retina. Eosinophils and some neutrophils also achieved the optic disc in response to LTB4. Tissue damage to the optic nerve head coincided with the presence of degranulating eosinophils, indicating that visual impairment may result from damage to the optic nerve head, with the retina left intact. Apart from the ora serrata and pars plana, no leukocyte infiltration in other anterior segment tissues--such as the pars plicata, ciliary process, or iris proper--was apparent.

It appears that the ingress of leukocytes into intraocular tissues of the eye in response to leukotrienes is discretely regulated, probably at the level of the vasculature.