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The Secret Weapon of B cells: Why do they recognize soluble antigens?
B cells play a crucial role on the wonderful stage of the immune system.These cells are not only the main force in antibody production, but also experts who can recognize various antigens.How can B cells recognize soluble antigens during this process?This has triggered in-depth exploration by scientists.
During antigen presentation, professional antigen presentation cells (APCs) bind antigens to the main histocompatibility complex (MHC) proteins, thereby displaying them on the cell surface, allowing T cells to be recognized by their T cell receptors (TCRs).
In the process of studying the immune system, researchers have found that almost all cell types can present antigens in some way.However, professional APCs such as dendritic cells, macrophages and B cells play a special role in this process, which effectively activate T cells and thus launch a strong immune response.This is because professional APCs express MHC class II and co-stimulatory molecules, which are key to B cells' recognition of soluble antigens.
The role of professional APCs and B cells
Professional antigen presenting cells mainly include dendritic cells, macrophages and B cells.As the "monitor" in the atmosphere, B cells can interact directly with soluble antigens bound to their specific B cell receptors.This ability allows B cells to detect foreign antigens in a timely manner and initiate the process of antibody production.
B cells can undergo antibody type transition and affinity maturation during interaction with T-aid cells, which allows B cells to produce more efficient antibodies against the same antigen.
When B cells recognize antigens, they internalize them and use MHC class II molecules to present processed antigen fragments to T help cells.At this time, T cells recognize these antigen MHC complexes through TCR and are eventually activated through the assistance of costimulation signals.This process not only improves the immune response ability of B cells, but also helps the formation of memory cells.
The pioneering role of dendritic cells
Dendritic cells are considered to be the most critical role among professional APCs.These cells have excellent antigen capture capabilities and are able to effectively capture foreign pathogens and present them to T cells.When encountering pathogens, dendritic cells mature and significantly increase their MHC and co-stimulatory molecules expression, thereby activate T cells more effectively.
Dendritic cells not only cross-present antigens, but also play an important role in preventing autoimmune diseases, making them indispensable in immune defense.
These professional APCs play a key role in lymph nodes. In order to better interact with T cells, they transfer in the flow of lymph, ultimately helping to activate T cells and enhance the efficiency of the overall immune response.
Application in cancer treatment
APCs also play an important role in cancer research and treatment.By stimulating B and cytotoxic T cells, APCs can help produce antibodies against tumor-associated antigens and clear malignant cells.More and more cancer treatment options are based on this principle, which enhances the body's immune response by activating dendritic cells or introducing specific T cells.
The new generation of cancer therapies have even begun to use genetic engineering to create artificial antigen presenting cells to encourage the immune system to attack tumor cells, showing potential that traditional therapies cannot match.
These artificial APCs can hold the necessary MHC proteins, co-stimulatory molecules and specific peptides in the hope of activate an immune response to fight cancer cells.Among them, the APC activator IMP321 is in clinical trials to accelerate the immune response to eliminate metastatic breast cancer or melanoma.
As we become more and more aware of the immune system, our understanding of B cells and APCs is also expanding.How exactly does the perfect collaboration of these cellular mechanisms shape our immune defense line?
