MURINE THYMIC NURSE CELLS AND ROSETTES - ANALYSIS OF ADHESION MOLECULE EXPRESSION USING CONFOCAL MICROSCOPY AND A SIMPLIFIED ENRICHMENT METHOD

Thymic nurse cells (TNO and T-cell stromal rosettes (ROS) are two in v ivo models for stromal cell-thymocyte interactions. We describe a simp lified enrichment method for TNC and ROS that overcomes the necessity for large amounts of tissue. The complexes were further analyzed with confocal microscopy, and three subunits of ROS were defined on the bas is of their central cell phenotype, i.e., macrophage, dendritic, or ep ithelial cell rosettes. Because adhesion molecules are proposed to pla y a crucial role in T-cell development, we investigated CD44, LFA-1, a nd ICAM-1 expression in such complexes. The epithelial component of TN C expresses CD44 and ICAM-1, whereas intra-TNC thymocytes are LFA-nega tive. With regard to ROS, all subsets expressed CD44, and macrophage a nd dendritic cell ROS were also ICAM-1-positive and LFA-1-positive. Th e current protocol opens the possibility for further in vivo analysis of stromal cell-thymocyte interactions, e.g., for studies of scarce ge ne mutant mice.