A contribution to the immunopathology of vernal keratoconjunctivitis

Abstract

The tear fluid contains proteins which are synthesized locally in the conjuncfiva and lacrimal glands, and others, which reach the tear fluid from the blood circulation. It is generally accepted that serum albumin (HSA) belongs to the latter group of tear proteins. Consequently, the ratio between tile levels of HSA in the tear fluid and in the blood serum can be used as a parameter for the degree of vascular leakage. All blood-borue tear proteins will show concentration ratios in tears and blood serum similar to HSA, provided that they pass through the blood-tear barrier at the same flow rate as HSA. This principle may be used to determine whether a certain tear protein is blood-borne or locally synthesized. An additional method to determine the source of tear proteins is supposed, and is based on the assumption that blood-borne proteins will occur in tears from both eyes at a concentration ratio similar to that of HSA, whereas the concentration ratios of locally synthesized proteins will not be related to the HSA-levels in the tears of the two eyes. This method is independent of the rate of diffusion through tissue barriers.In the present study these methods have given coordinating and supplementary information. The IgG and IgM contents of tears from healthy eyes and from patients with vernal keratoconjunctivitis (VC) were shown to be essentially blood-borne. In tears from VC-pafients as well as from healthy controls, IgE was usually found to be a product of local synthesis. In tears from healthy eyes, IgA was almost entirely synthesized locally, but a significant part of the IgA in tears from inflamed eyes was blood-borne.The geometrical mean (GM) of blood levels of IgE for VC-patients was not increased in relation to the GM for healthy controls of the same age groups. In contrast, the GM for IgE in tears from VC-patients (27.5 I.U./ml) was higher than the GM + 2 SD for the healthy controls (4.1 I.U./ml) and also than the highest level of IgE observed in tears from healthy eyes (6.6 I.U./ml). The tear-levels of IgE for VC-patients were strikingly dynamic and in some patients a hundred-fold increase or decrease was observed in the course of a relatively short time period. In contrast, alterations of blood-levels of IgE and of tear levels of IgA were relatively moderate. These results indicate a marked association between VC and an increased IgE-content of tears derived from local immunocytes. However, in some patients apparently suffering from typical VC, normal IgE-levels were consistently found in tears from both eyes during a number of relapses or aggravations of the disease. These results may indicate that more than one etiopathogenesis may lead to the clinical condition known as VC. A hitherto unexplained feature of VC is the pronounced lacrimation. We have shown that the concentration of the essential tearproteins is not decreased in VC. Lacrimation is therefore associated with accelerated protein synthesis of the secretory system.

Allergen-Specific Immunoglobulin E Antibodies in Tears and Serum of Vernal Conjunctivitis Patients

“…The disease is usually assumed to be an IgE-mediated allergic disorder, and this concept is supported by biochemical [3], immunological [4][5][6][7] and cytological [8] studies, although we have previously shown that in a significant minority of the cases IgE levels of tears and serum remain low throughout [4,9,10]. Some authors have demonstrated antipollen antibod ies of the IgE [5,6] and IgG [11] type in tears of vernal conjunctivitis patients, but since the disorder is not markedly season-linked in this area, we have studied the occurrence of IgE antibodies to a broad spectrum of allergens.…”

“…Similar results were obtained with 'all samples'. For healthy individuals, GM of tear IgE = 0.95 IU/ml (4). "This part of the table is based on samples obtained during periodical observation of the patients, in most cases during 2 years or more.…”

Vernal Keratoconjunctivitis: The Significance of Immunoglobulin E Levels in Tears and Serum

“…The mean level of HSA in tears of healthy eyes has previously been determined to 17.7 ±12.6 (±SD) mg% [14]. For all 27 patients of this study, mean tear HSA was 408.7 ±284.9 mg% (446 samples from 54 eyes).…”

“…Plots to the right of this line indicate local production of tear IgE. The fraction x-y/x indicates the minimal propor tion of tear IgE that is synthe sized locally [14]. The regres sion of the plot is y = 0.08x + 60.9; correlation coeffi cient r = 0.4528; p < 0.001.…”

House Dust Mites and Vernal Keratoconjunctivitis

“…1). The disease is assumed to be main ly an IgE-mediated allergic disorder [7], although the chronic inflammatory and pro liferative states in VKC lead some authors to believe the pathogenesis of VKC to be type IV cutaneous basophil hypersensitivity as well as type I allergy [8,9], The aim of this study is to determine the relationship between the presence and sea sonality of the house dust mite population in the VKC patients' homes and the severity of their symptoms.…”