Differential Activation and Apoptotic Response of Human Lymphocytes to TCR Stimulation Among Non–Infectious Uveitis Patients and Normal Donors

Abstract

Purpose: : Although current literature strongly suggests that primarily T cells mediate the pathogenesis of non–infectious intraocular inflammatory diseases, we know little about the rate of activation and the pattern of the fate of lymphocytes after T cell receptor (TCR) stimulation in these patients. In this study, we examined the rate of proliferative response and the apoptosis pattern of peripheral blood mononuclear cells (PBMCs) isolated from non–infectious uveitis patients after TCR stimulation. We wish to analyze and correlate the patterns with the clinical activities and facilitate clinical interpretation and treatment.

Methods: : PBMCs were isolated from the whole blood of 4 normal donors and 6 uveitis patients and a T–Cell proliferation assay was performed at 5 different time points after TCR stimulation in serum free media. ΔCPM (counts per minute) was calculated to compare proliferative response. The apoptosis pattern was determined by flow cytometry analysis of Annexin V and Viaprobe staining of the T cells after TCR stimulation.

Results: : Active uveitis patients demonstrated an earlier onset of proliferative response to TCR stimulation than those of normal donors and inactive patients as shown by the slope of ΔCPM. The peak ΔCPM was highest in the active patients, 2^nd highest in the inactive patients and lowest in the normal donors. These differences were statistically significant as early as 30h after stimulation and lasted up to 90h after stimulation (p ≤ 0.001 using 1–way between subjects ANOVA). The apoptosis assay showed an increased rate of early and late apoptosis of CD3+ T cells in patients as compared to normal donors. It is of particular interest to observe that one patient who has been clinically quiescent for >1 year showed a much greater apoptosis response to TCR stimulation than others.

Conclusions: : We observed a potentially differential pattern of activation and apoptotic response of human lymphocytes to TCR stimulation in non–infectious uveitis patients vs. normal donors. These findings suggest that in addition to antigen–specific autoreactive T cell response, there is an imbalanced regulation of the lymphocytes to TCR stimulation in autoimmune uveitis patients. In addition, while apoptosis can’t solely account for the differential patterns of T cell activation among the patients and normal donors, increased apoptosis may contribute to the clinical quiescence of some uveitis patients after long–term successful management.

Keywords: proliferation • apoptosis/cell death • autoimmune disease