The establishment of immune system is an orchestrated process from hematopoietic stem cells to immune effector cells.Hematopoietic stem cells development into variety of immune cell subsets with high pluripotency.However,effector immune cells possess specific function with limited pluripotency.Recently,researchers found that differentiated immune cells were able to transdifferentiate to other cell types accompanied with the conversion of effector functions.The plasticity of immune cell subsets were confirmed in many subsets such as T cell,innate lymphoid cell,macrophage,neutrophil and so on.The transdifferentiation of immune cells is accompanied with the process of many diseases.Study on plasticity of immune cells will provide important theoretic basis to clinic trail.In this review,we summarized the subsets,regulatory mechanism,and related diseases about immune cell plasticity.

Cancer stem cells (CSCs), a small subset of cells in the tumor bulk with the ability of self-renewal and differentiation, are the key to tumor occurrence, metastasis, drug resistance and relapse. CSCs are resided in a specific microenvironment, and their number maintenance, self-renewal and differentiation are precisely regulated by the microenvironment, and the immune microenvironment is one of the most critical microenvironments for CSCs. In recent years, tumor immunotherapy has achieved great success, but drug resistance and recurrence are frequently occurred after immunotherapy. Compared with non-CSC tumor cells, CSCs harbor stronger immune escape ability, and their roles in tumor immune escape are increasingly followed. In this review, we described the discovery history and lineage sources of CSCs, focused on immune cells in the CSC microenvironment, such as tumor-infiltrating lymphocytes, tumor-associated macrophages, and tumor-associated dendritic cells, and analyzed the mechanism of CSC-immune cell interaction. Intervention strategies targeting CSCs and their immune microenvironment are also described. With the development and application of advanced technologies such as CSC-immune cell co-culture, single-cell sequencing and lineage tracing, the immune escape of CSCs can be suppressed by targeting the interaction between CSCs and immune cells or reversing the immunosuppressive microenvironment, which is expected to provide potential solutions to the problems of drug resistance and relapse in tumor immunotherapy.