Stefan D. Trocme

Conjunctival Deposition of Eosinophil Granule Major Basic Protein in Vernal Keratoconjunctivitis and Contact Lens-Associated Giant Papillary Conjunctivitis

To investigate the role of the eosinophil in vernal keratoconjunctivitis and contact lens-associated giant papillary conjunctivitis, we assessed the presence of eosinophil granule major basic protein in conjunctival tissues by immunofluorescence. Biopsy specimens of conjunctiva were taken from nine patients with vernal keratoconjunctivitis, seven patients with giant papillary conjunctivitis, and five control subjects. We performed a masked semiquantitative assessment of immunofluorescence on sections from each specimen. The vernal keratoconjunctivitis and giant papillary conjunctivitis groups had significantly (P less than .05) more major basic protein deposition than controls. No significant correlation between severity of disease and degree of major basic protein deposition was found. We found extracellular eosinophil granules in one of three vernal keratoconjunctivitis specimens examined by transmission electron microscopy. Thus, eosinophil degranulation commonly occurs in vernal keratoconjunctivitis and giant papillary conjunctivitis with release of eosinophil granule major basic protein and presumably other toxic granule proteins onto affected tissues. These cationic proteins are potent cytotoxins and are able to stimulate mast cell degranulation.

Structural and Functional Studies of the Corneal Endothelium in Diabetes Mellitus

We performed specular microscopy, anterior segment ocular fluorophotometry, corneal pachymetry, and tonometry on 14 patients with chronic type I diabetes and nonproliferative retinopathy and on 14 age-matched control subjects. The eyes of patients with diabetes had an increased coefficient of variation of endothelial cell area, a decreased percentage of hexagonal endothelial cells, increased corneal autofluorescence, and increased intraocular pressure, which confirmed previous studies. There was no difference, however, in corneal thickness or endothelial permeability to fluorescein. Thus, we were unable to detect any abnormality in endothelial function in these diabetic corneas in the unstressed state, despite structurally abnormal endothelial cells.

Medical Therapy for Ocular Allergy

The ocular manifestations of allergy have traditionally been classified into four categories--namely, hay fever conjunctivitis, vernal keratoconjunctivitis, atopic keratoconjunctivitis, and contact lens-associated giant papillary conjunctivitis. Typically, hay fever conjunctivitis is characterized by mild conjunctival inflammation, whereas the other disorders may have severe inflammation and clinical manifestations. Potentially blinding corneal complications may result from vernal keratoconjunctivitis and atopic keratoconjunctivitis. Although hay fever conjunctivitis is clearly an immediate hypersensitivity reaction, the immunologic mechanisms that cause vernal keratoconjunctivitis, atopic keratoconjunctivitis, and giant papillary conjunctivitis are primarily unknown and speculative. Treatment of patients with ocular allergies is often challenging and may necessitate collaborative efforts of an ophthalmologist and an allergist. Herein we discuss conventional therapy and new, promising antiallergy drugs.

Human and experimental lens repair and calcification

Lens repair and calcification have been studied in an experimental rabbit model of anterior segment necrosis. Findings were compared with those in a human senile cataractous lens with subcapsular calcification. Rabbit lenses subjected to anterior segment ischemia underwent a repair process similar to that observed in perforating lens injuries. Cellular response included the formation of fibroblast-like cells that covered epithelial defects of the anterior pole. These observations suggest that the lens epithelium can transform into fibroblast-like cells. The calcification process was a non-cell-induced, and the observed mineral was probably nucleating on organic molecules. Elemental analysis demonstrated that crystals contained calcium and phosphorus with a ratio of 2:1. The mineral was probably hydroxyapatite. Since morphological findings in rabbit lenses closely resemble those of the studied cataractous human lens, the rabbit model appears to simulate one type of lens calcification in senile cataract.

Late-phase reaction in topically induced ocular anaphylaxis in the rat

A cellular late-phase reaction is described in a rat model of topically induced ocular anaphylaxis. Rats were immunized with dinitrophenylated Ascaris suum extract and alum and were tested for active cutaneous anaphylaxis on day 13. Rats with a strong skin test response were selected for ocular challenge with di-DNP-lysine. Macroscopic observation and histologic evaluation were performed at 1, 6, and 24 h. In rats showing a moderate macroscopic ocular response at 1 h, mast cell degranulation was significantly increased at 1 h; no significant increase in eosinophils, neutrophils or lymphocytes was found in the conjunctive of these animals. In rats showing a marked macroscopic ocular response at 1 h, mast cell degranulation was significantly increased at 1 and 6 h; the number of eosinophils was significantly increased at 1 and 6 h, and of neutrophils at 6 h only. At 24 h, neutrophil and eosinophil numbers returned to baseline levels. There was no macroscopic evidence of a late-phase response in either group of animals. Our results suggest that, in keeping with earlier observations in human skin, a strong early response to antigen is required for the development of a late-phase ocular response in the rat.

Topically induced ocular anaphylaxis in rats immunized with egg albumin

A model of topically induced ocular anaphylaxis was developed. Male Sprague-Dawley rats were immunized by intraperitoneal injections of egg albumin (EA) and alum and topically challenged with EA. Application of EA induced clinical (conjunctival edema) and histologic (mast cell degranulation) signs of anaphylaxis, when the antigen was preceded by topical application of dithiothreitol (DTT), a mucolytic agent. Rats challenged by four EA applications did not differ significantly in clinical edema or mast cell degranulation from those challenged by one EA application at the same (0.1 M DTT) pretreatment level, but there was significantly greater histologically assessed edema in the eyes challenged four times.

Late-phase reaction and tear fluid cytology in the rat ocular anaphylaxis.

Tear fluid cytology is described for the early and late phases of ocular anaphylaxis in actively immunized Sprague-Dawley rats. Tears were collected from both eyes of the rats before challenge and at 1, 2, 4, 6, 8, 10, 12, 24, and 48 h after topical challenge with di-DNP-lysine in one eye and PBS in the fellow eye. Results showed a statistically significant increase in the Aggregate Cell Rating, which represents the aggregate scores in neutrophil, eosinophil, lymphocyte, and atypical epithelial cell levels, in antigen-treated vs control eyes. This report is the first to use a cytologic study of tear film to detect the late phase of ocular anaphylaxis in the rat. Cytology of the tear film could be applied to the study of allergic conjunctivitis in both animals and humans.

Worm antigen-induced ocular anaphylaxis in rats infected with Nippostrongylus brasiliensis

A model of topically induced conjunctival anaphylaxis has been developed. Male Sprague-Dawley rats were immunized by infection with 3000 Nippostrongylus brasiliensis larvae and challenged topically on the eye 4 weeks later. Application of worm antigen alone did not induce clinical (conjunctival edema) or histologic (mast-cell degranulation) signs of anaphylaxis. Topical challenge with antigen 15 min after topical application of dithiothreitol (DTT), a mucolytic agent, elicited conjunctival edema and mast-cell degranulation within the first hour after challenge. At 6 and 24 hr, no clinical change was evident and conjunctival mast cells had again become granulated. At none of the three intervals (1, 6 and 24 hr) was there a significant increase in neutrophils, lymphocytes, eosinophils or macrophages in tissues from DTT-pretreated, antigen-eyes. The present model of ocular anaphylaxis resembles the ocular component of human hay fever in that sensitization prior to challenge is essential, the antigen is presented topically to the ocular tissues, conjunctival edema is the clinical manifestation and mast cell degranulation characterizes the histologic changes.

Characteristics of the Cellular Response of the Rat Conjunctiva to Topically Applied Leukotriene B4

Cellular events in the rat conjunctiva were studied at 1, 6 and 24 h following the topical application of leukotriene B4. A significant increase was noted in the number of eosinophils (p less than 0.01) and neutrophils (p less than 0.05) at 1 h and only in eosinophils at 6 h after leukotriene B4 application at the 2-micrograms dose. At the 200-ng dose, the eosinophil count was significantly elevated at 1 h only, and the number of neutrophils was not significantly changed at any time point. No significant increase in cell counts was observed at the 20-ng dose. In conclusion, certain doses of topically applied leukotriene B4 significantly increased the number of eosinophils and neutrophils in the rat conjunctiva.

Effects of topical pre-treatment with dexamethasone on the immediate and late phases of topically induced ocular anaphylaxis in the rat

Abstract. We tested the effects of pre‐treatment with dexamethasone on topically induced ocular anaphylaxis in the rat. Rats were immunized with dinitrophenylated Ascaris suum extract and challenged with di‐DNP‐lysine. Dexamethasone was administered topically once (24, 6, or 1 h before challenge) or three times (6, 4, and 2 h before challenge). A single pre‐treatment given at 24 or 6 h had no significant effect. A single pre‐treatment 1 h before challenge reduced the extent of edema assessed histologically but not clinically, and had no significant effect on the eosinophil count in conjunctival tissue examined 6 h after challenge. Eyes pre‐treated with dexamethasone 6, 4, and 2 h before challenge showed a significant reduction in conjunctival edema assessed histologically and clinically 1 h after challenge. In addition, 6 h after challenge the number of eosinophils was significantly reduced. We conclude that repeated pre‐treatment with dexamethasone can suppress both the immediate phase and the cellular late phase of topically induced ocular anaphylaxis.