The human thymus microenvironment: heterogeneity detected by monoclonal anti-epithelial cell antibodies

Monoclonal antibodies were raised against human thymus stromal cells and their specificity for the epithelial component of thymus stroma assessed by double immunofluorescence using anti-keratin antibodies to identify epithelium. Our monoclonal antibodies identify six distinct patterns of epithelial cell antigen expression within the thymus: pan epithelial (antibody IP1); cortex (MR3 and MR6); cortical/medullary junction (IP2); subcapsule and subpopulation of medulla (MR10/MR14); Hassall's corpuscles and adjacent subpopulation of medulla (IP3); Hassall's corpuscles only (MR13/IP4). This heterogeneity of antigen expression suggests that many different epithelial microenvironments exist within the human thymus.