Ultrastructure and Function of Conjunctiva-Associated Lymphoid Tissue in a Novel Mouse Model

Abstract

Purpose: : Conjunctiva-associated lymphoid tissue (CALT) is thought to play a key role in the initiation of ocular surface-related immune responses. Our introduction of a novel mouse model and optional two-photon microscopy for intravital imaging enables functional studies such as analysis of lymphocyte subsets, antigen transport and dynamic changes of CALT. Here we present results of ultrastructural analyses of CALT in our animal model and leadoff functional experiments.

Methods: : Female Balb/c mice were topically challenged with Ovalbumin and cholera toxin B to induce CALT. A panel of antibodies and conventional histological techniques were used for ultrastructural analysis of CALT induced. Stimulated mice were euthanized at different time points to analyze the long term progress of CALT. T-cells from DO11.10 mice were adoptively transferred in prior stimulated mice and confocal microscopy was used to identify transferred cells within CALT after OVA323-339 application. Uptake of fluorescing microspheres was demonstrated in-vivo by intravital two-photon microscopy

Results: : CALT consisted of lymphoid follicles with B- and T-cells and dendritic cells. Lymphoid and blood vessels were located adjacent to the follicle. Follicles remained present at least for 8 weeks. Adoptively transferred T-cells rapidly migrated into CALT 1 hour after antigen challenge. Fluorescent microspheres were taken up preferentially by the lymphoepithelium of CALT.

Conclusions: : Our mouse model demonstrates all components of human CALT and therefore is suitable for functional studies concerning ocular surface-related immune responses. The investigation of antigen-uptake, immediate and prolonged immune responses and its further modulation will help to understand the role of CALT to maintain the integrity of the ocular surface.

Keywords: conjunctiva • antigen presentation/processing • immunomodulation/immunoregulation