The ocular secretory immune system: A review

Abstract

The majority of immunoglobulin in tears is of the immunoglobulin A (IgA) isotype, which is produced mainly by plasma cells of the lacrimal gland. The mechanism responsible for the lodging of the IgA cells in this gland is unknown and probably not dependent on direct glandular encounter with antigen. Previous experiments have suggested that a T_h cell from the lacrimal gland can influence B lymphocytes to differentiate into IgA plasma cells. Mechanisms responsible for the IgA-specific T_h cell accumulation in the LG could be related to nervous system influences, possibly neuropeptides. These effects on T_h cells could be mediated either directly or through lacrimal gland epithelial cells. Such a mechanism could explain the presence of IgA-producing plasma cells in the lacrimal gland, and would allow strategies for manipulation of this important first line defense immune system.