Exp. Eye Res. (1997) 65, 803–808 Further Studies on the Immunopathology of Atopic Keratoconjunctivitis using Flow Cytometry AVNI MURAT AVUNDUK a *, MUSTAFA CIHAT AVUNDUK b , VOLKAN DAYANIR c  YAVUZ TEKELIOGLU d a Karadeniz Technical University, School of Medicine, Department of Ophthalmology, Trabzon, Turkey b Selc  uk University School of Medicine, Department of Pathology, Konya, Turkey c Eskis  ehir Air Force Hospital, Department of Ophthalmology, Eskis  ehir, Turkey and d Karadeniz Technical University, School of Medicine, Department of Histology, Trabzon, Turkey (Received Lund 1 April 1997 and accepted in revised form 4 August 1997) Atopic keratoconjunctivitis (AKC) is an ocular manifestation of systemic hypersensitivity. Although the pathogenesis of AKC is not fully understood, some previous data suggest that a decrease in numbers of suppressor T lymphocyte (Ts) and increase of Th, especially Th2 (the second subgroup of helper T lymphocyte), at the ocular surface may play an important role in the occurrence of the disease. In this study, the percentages of naive-Th (CD445RA) and memory-Th (CD429) cells, and the ThTs and memory-Th cellsnaive-Th cells ratios were measured in the blood and tear samples of patients with AKC, atopic patients without ocular involvement and normal volunteers, using flow cytometry. Groups were compared using the Mann-Whitney U test. We found that patients with AKC had significantly higher memory-Th cell concentration, and ThTs and memory-Th cellsnaive-Th cell ratios both in the tear and blood samples compared to normal subjects. While no significant difference existed between the tear samples of the atopic patients without ocular involvement and normal volunteers with respect to the above values, atopic patients had higher percentages of memory-Th cells and higher ThTs and memory- Th cellsnaive-Th ratios in their blood than normal subjects. The percentages of memory-Th cells, and the ThTs and memory-Th cellsnaive-Th cell ratios in the tear samples of AKC patients were also found to be higher than that of the atopic patients without ocular involvement, but no significant difference was present between the blood samples of these groups. The percentages of naive-Th cells did not show any significant difference between groups either in tear or blood samples. Since the mean memory-Th cellsnaive-Th1 cells ratio in the tear samples of the patients with AKC was higher than in their blood samples, we propose that the localized accumulation of memory-Th2 cells, in addition to the increase of ThTs ratios in the external eye may cause AKC in atopic individuals.  1997 Academic Press Limited Key words : human ; tear analysis ; atopic keratoconjunctivitis ; flow cytometry ; helper T lymphocyte ; suppressor T lymphocyte ; memory T helper lymphocyte. 1. Introduction Atopic keratoconjunctivitis (AKC) is an ocular mani- festation of a systemic hypersensitivity. The primary criterion for the clinical diagnosis of AKC is the demonstration of a specific form of a chronic con- junctivitis andor keratitis in association with atopic dermatitis (eczema) (Hogan, 1952). It is reported that AKC is more frequently seen in males than females (Foster and Calonge, 1990 ; Jay 1981 ; Buckley, 1989). Conjunctival involvement occurs in approximately 16 % of patients with atopic dermatitis (Garrity and Liesegang, 1984). Conjunctival inflammation is char- acterized by itching, burning and mucoid discharge. Conjunctiva is pale and congested, and a medium to severe papillary response is usually present on the upper tarsal conjunctivaly (Tuft et al. 1991). There may be associated corneal disease present in some patients. The most commonly encountered corneal finding is punctate keratitis which is most prominent * Correspondence to : Avni Murat Avunduk, KTU  Lojmanları, No: 3117, 61080 Trabzon, Turkey. inferiorly. Marginal ulceration, vascularization, and stromal opacification can also occur (Hogan, 1952). The pathogenesis of atopic dermatitis and kerato- conjunctivitis is not fully understood, but the role of immediate-type hypersensitivity is suggested by a high incidence of positive immediate type skin test reac- tions, elevated serum IgE levels in more than 80% of patients, and frequent eosinophilia (Arffa, 1991 ; Rocklin and Pincus, 1986). On the other hand, some impairment in the cell mediated immunity is also proposed in atopic individuals. The number of sup- pressor T cells (Ts) was reported to be decreased in patients with active disease and in-vitro studies demonstrated decreased suppression of IgE synthesis by Ts cells in patients with atopic dermatitis (Leung, Rhodes and Geha, 1981 ; Hemady, 1985). This current study was designed to investigate the possible role of T cells in the pathogenesis of disease. The T helper (Th)Ts (CD4CD8) and naive-Th (A subgroup of Th cells)memory-Th (Another subgroup of Th cells) cell ratios and the percentages of naive-Th cells and memory-Th were measured in the tear and 0014–48359712080306 $25.000ey970398  1997 Academic Press Limited