Cell surface antigens, also known as cell membrane antigens or surface markers, are molecules that are expressed on the outer surface of cells, particularly immune cells. These antigens play a crucial role in cellular recognition and communication, as they allow cells to distinguish self from non-self and regulate immune responses.
Cell surface antigens are primarily proteins or glycoproteins, although lipids and carbohydrates can also act as antigens. They provide a means of identifying different cell types and are responsible for many cellular functions, including cell adhesion, receptor-mediated signaling, and immune cell activation.
The presence or absence of specific cell surface antigens can be used to classify cells into distinct types or subsets. For instance, immune cells such as T cells, B cells, and natural killer cells can be distinguished from one another based on the expression of different cell surface antigens. Additionally, certain cell surface antigens are associated with specific diseases, such as certain types of cancer or autoimmune disorders, and can be used as diagnostic markers.
Cell surface antigens are often targeted by the immune system during immune responses. Antibodies, produced by B cells, can bind to these antigens, marking them for destruction by other immune cells. This immune recognition of cell surface antigens is essential for immune surveillance, defense against pathogens, and maintenance of immune tolerance.
In summary, cell surface antigens are molecules expressed on the outer surface of cells that play a crucial role in cellular recognition, communication, and immune responses. They have diverse functions and are used to classify cells, diagnose diseases, and trigger immune reactions.
