Antigenigenkänning

Antigenigenkänning is a fundamental process in immunology that describes how the immune system recognizes foreign substances, known as antigens. Antigens are typically molecules found on the surface of pathogens like bacteria and viruses, or on abnormal cells, such as cancer cells. This recognition is crucial for initiating an appropriate immune response to neutralize or eliminate these threats.

The primary mechanisms for antigenigenkänning involve specialized immune cells, particularly lymphocytes. B cells and T cells are the main players. B cells possess B cell receptors (BCRs) on their surface that can directly bind to specific antigens. Upon binding, B cells can become activated, proliferate, and differentiate into plasma cells that produce antibodies. Antibodies are proteins that can neutralize antigens or mark them for destruction by other immune cells.

T cells, on the other hand, have T cell receptors (TCRs) that recognize antigens presented to them by other cells. This presentation is typically done by antigen-presenting cells (APCs), such as macrophages and dendritic cells, which process antigens and display fragments of them on their surface in conjunction with MHC molecules. Helper T cells (CD4+) and cytotoxic T cells (CD8+) have different roles in the immune response based on the type of antigen they recognize and the MHC molecule involved in its presentation. This precise recognition ensures that the immune system targets only foreign or abnormal entities, maintaining tolerance to the body's own tissues.