An evaluation of the role of leukocytes in the pathogenesis of experimentally induced corneal vascularization. III. Studies related to the vasoproliferative capability of polymorphonuclear leukocytes and lymphocytes.

Studies in the past have suggested that leukocytes are a prerequisite to corneal vascularization. To test this hypothesis further, experiments were conducted to determine whether the intracorneal instillation of polymorphonuclear leukocytes, lymphocytes, or components of leukocytes would induce a corneal vascular ingrowth. These cells or cellular fractions were injected intracorneally into Fisher albino rats whose circulating leukocytes had been depleted by total body x-irradiation. Polymorphonuclear leukocytes isolated from glycogen-induced peritoneal exudates caused a corneal vascular invasion, but lymphocytes obtained from thymus, spleen, and lymph nodes failed to do so. To learn whether an extractable factor could be isolated from polymorphonuclear leukocytes these cells were suspended in isotonic saline, ultrasonified and then centrifuged at 101,952g for 1 hour. Aliquots of the resulting sediment and supernatant were injected intracorneally into rats with radiation-induced leukopenia. The nonsedimentable supernatant caused corneal vascularization, but the sediment did not provoke the phenomenon. These studies not only provide further support for the hypothesis that leukocytes initiate corneal vascularization, possibly by the release of one or more heat labile chemical mediators, but directly implicate the polymorphonuclear leukocyte in this process.