Lymphoid stroma in all its states.

Stromal cells are found in all tissues of the body. Among them, lymphoid stromal cells (LSCs) correspond to the cell subsets found in secondary and tertiary lymphoid organs. LSC heterogeneity has been characterized in depth in mice based on cell-fate mapping, high-resolution imaging and single-cell RNAseq analysis, and more recently in humans despite the difficulty of accessing these rare cell populations. At steady-state, LSCs organize discrete anatomical niches in lymphoid organs and orchestrate adaptive immune response. Studies of LSCs at the single cell level have identified a wide role for these cells in various pathological conditions, including solid tumors, autoimmune diseases, and lymphomas. In this review, we will discuss the diversity and plasticity of LSCs and LSC-like cells as well as their functions in pathological settings, with a focus on cancer and autoimmune diseases. Altogether, it highlights the importance of increasing our understanding of these cells, to use them as a target for novel therapeutic strategies.