What is the role of antigens in the immune system?

The role of antigens in the immune system is primarily related to their function in mobilizing adaptive, or specific, defenses. Antigens are molecules or molecular structures that are recognized by antibodies or by T-cell receptors. When an antigen is detected by the immune system, it triggers a response, particularly from lymphocytes, which include T cells and B cells.

B cells, upon recognizing an antigen, are activated to produce specific antibodies that target that particular antigen, while T cells can directly attack infected or abnormal cells. This adaptive response is tailored specifically to the pathogen or foreign substance attempting to invade the body, allowing for a more effective and long-lasting immune response.

The other options, while they relate to the immune response, do not accurately capture the specific role of antigens. For instance, enhancing the inflammatory response is a function of other immune components, not antigens directly. Acting as a physical barrier is typically a characteristic of the skin and mucous membranes, rather than the role of antigens. Lastly, while the immune response does ultimately lead to the destruction of pathogens, antigens themselves do not carry out this function; rather, they serve to activate the immune system's components to perform this task.