PHENOTYPIC ANALYSIS OF RESIDENT LYMPHOID-CELLS IN THE CONJUNCTIVA ANDADNEXAL TISSUES OF RAT

The conjunctival associated lymphoid tissue is considered to be an int egral part of the mucosal immune system, Under normal circumstances im mune mechanisms in mucosal associated lymphoid tissue of the gut and b ronchus can selectively suppress, rather than enhance, immune responsi veness to encountered antigens, inducing a state of tolerance. It is p ossible that conjunctival associated lymphoid tissue can also induce a state of tolerance to encountered antigens. Such a response may be ex ploited to modulate immune mediated ocular disease. Enhanced tolerance may protect the host against foreign antigen. Alternatively, under ce rtain circumstances when the normal immune system is altered or disrup ted the mucosal tissue may act to induce sensitisation and trigger imm une mediated disease. The rat is frequently used as an animal model of immune mediated eye disease, but the normal profile of immune cells i n the rat conjunctiva has not been studied, This information is essent ial for meaningful interpretation in the experimental situation. In th is study we examined the immunophenotype of lymphoid tissue associated with the conjunctiva, lacrimal gland and Harderian gland of the Lewis rat. CD4(+), Ia(+) and the monocyte/macrophage population of cells we re found predominantly in the substantia propria of the conjunctiva an d interstitial connective tissue of the glands. CD8(+) cells were dist ributed mainly in relation to the conjunctival and glandular epitheliu m. Goblet cells stained strongly with the monoclonal antibody (MAb) MR C OX-39, which is a marker for IL-2 receptors. The overall pattern of distribution of immunocompetent cells in the rat was found to be simil ar to that reported in humans. (C) 1997 Academic Press Limited.