Although immune cells play a critical role in human diseases such as infection and cancer, structural cells including endothelial and stromal cells are also crucial for maintaining the function of the immune cells. Recent single-cell technologies showed multiple heterogenous subsets in structural cells that have not been considered before. The aim of our group is (1) to find unrecognized heterogeneous structural cell subsets in human organs including lymphoid organs and tumors using single-cell technologies, and (2) to find the new molecular mechanism between heterogeneous structural cells and immune cells in health and disease.