An antigen is a substance that triggers an immune response in the body.

An antigen-presenting cell (APC) or accessory cell is a cell that displays an antigen bound by major histocompatibility complex (MHC) proteins on its surface; this process is known as antigen presentation.

The cell membrane, or plasma membrane, is a biological membrane that surrounds the cytoplasm of cells.

In immunology, an immunological synapse (or immune synapse) is the interface between an antigen-presenting cell or target cell and a lymphocyte such as a T cell, B cell, or natural killer cell.

Immunology is the branch of biomedical science that focuses on the study of the immune system, including its structure, function, and ability to defend the body against foreign substances and diseases.

A lymph node is a small, bean-shaped organ located throughout the body that plays a crucial role in the immune system.

Platelets, also known as thrombocytes, are tiny blood cells that play a crucial role in preventing excessive bleeding.

The Wikipedia page for T-cell receptor provides a detailed overview of the structure, function, and importance of T-cell receptors in the immune system.