The Antigenic Determinant That Defines Thymic Nurse Cells Is Expressed by Thymic Epithelial Progenitor Cells.

Stromal thymic epithelial cells with the multicellular structure unique to thymic nurse cells (TNCs) express the pH91 antigen on their cell surfaces. The multicellular TNC-complexes develop through an intimate association between αβTCRCD4CD8 thymocytes and pH91-expressing cortical epithelial cells. TNCs participate in MHC-restriction and exhibit epithelial cell progenitor characteristics.