Introduction to dendritic cells

In 1973, Steinman and Cohn found a uniquely shaped cell with dendrites in the mouse spleen and named it a dendritic cell (DC). With the deepening of research on DCs from different tissue sources, the currently known subpopulations of DCs include classical DCs (cDCs) present in lymphoid tissues, blood and non-lymphoid tissues, and plasmacytoid DCs secreting type I interferons. (plasmacytoid DC, pDC). The main role of classical DC is to induce specific immune responses against invading antigens and maintain self-tolerance. The main role of plasmacytoid DCs is to produce large amounts of type I interferons and to stimulate corresponding T against microorganisms, especially viral infections. cell.

Current research shows that DC plays an important role in antigen presentation, the most important part of the immune response. It is currently recognized as the most powerful full-time antigen presenting cell in vivo. Under immunostable state, DCs distributed in peripheral non-lymphoid tissues are in an immature state, and their main function is to recognize and take up antigens. Compatible with its function, the immature DC surface expresses low levels of MHC class II molecules and costimulatory molecules, and highly expresses a range of receptors to facilitate identification of pathogen-associated substances, including multiple Toll like receptors (Toll like receptors, TLR), C-type lectin such as mannose receptor, DEC205 and the like.

In the event of infection or tissue damage, immature DCs migrate to the inflammatory site, and a series of changes occur in the immature DC, obtaining a mature phenotype and function: (1) loss of receptors for phagocytosis; (2) High expression of MHC class II molecules and costimulatory molecules, including CD40, CD80 and CD86; (3) morphological changes; (4) initiation of antigen processing mechanisms, including increased levels of lysosomal associated membrane proteins (DC-LAMP) . At the same time, the expression profile of chemokine receptors in mature DCs changed, the expression of CCR1, CCR5 and CCR6 decreased, while the expression of CCR7 increased, which promoted the migration of DCs from peripheral tissues along the afferent lymphatic vessels to adjacent secondary lymphoid tissues. Where, DCs meet antigen-specific initial T cells, induce their activation and proliferate into effector T cells, thereby initiating an immune response.

It can be seen that DC has different phenotypes and functions in the immature and maturity stages. By testing it, it will provide clues for studying the differentiation and development and function regulation of DC.