Kinetics of Immune Cell Migration Across the Conjunctival Basement Membrane

Abstract

Abstract: : Purpose:Immune cell migration from the lamina propria to the epithelium represents an important form of host defence against injury at mucosal surfaces. Our aim was to study the migratory patterns of the different subsets of immune cells that migrate from the lamina propria to the surface of the conjunctiva following injury. Methods:Human bulbar conjunctiva from cadavers consented for transplant and research were completely denuded of the epithelium in sodium ethylene diamino-tetra-acetic acid (EDTA). De-epithelialised samples were maintained in culture for 24, 48 and 72 hours. Cell migration from the lamina propria through the basement membrane was characterised by electron microscopy and fluorescence activated cell sorting analysis. Results:Electron microscopy revealed numerous pores in the denuded basement membrane in continuity with a network of communicating channels in the lamina propria through which large numbers of cells constantly migrated following loss of the epithelium. The number of cells that migrated in the first 24 hours was significantly greater than at 48 and 72 hours (p < 0.05). Majority of the migrating cells were T lymphocytes of which the CD4 subtype was predominant with very few B cells. Some cells expressed the Human mucosal lymphocyte-1 antigen (HML-1) in the absence of epithelial cells. There was no significant increase in the number of cells of the various subsets with time except B cells (p = 0.002). Conclusion:Large numbers of immune cells mainly CD4+ T lymphocytes selectively and continuously migrate through distinct channels in the lamina propria and pores in the basement membrane of the conjunctiva in response to tissue injury. HML-1 expression by migrating cells does not depend on interaction with epithelial cells.

Keywords: 365 conjunctiva