Flow cytometric analysis reveals unexpected shared antigens between histologically defined populations of thymic stromal cells

Utilizing flow cytometry, the expression of antigens recognized by six thymic stromal cell (TSC) reactive mAbs was investigated on fresh TSCs and TSC lines. It was found that some thymic epithelial cells and dendritic cells share antlgenlc phenotypes, and that most TSC reactive mAbs have a more extensive distribution than would have been predicted from immunohlstology. While these findings illustrate the higher sensitivity of flow cytometric analysis, they more Importantly emphasize the great complexity of TSC that direct T cell development. In order to Identify the molecular parameters that define the various steps involved in T cell differentiation, TSC antigens (non-TCR/MHC/co-receptor) that are functional will have to be Identified. This study represents the initial steps in characterizing such antigens.