Actin is a family of globular multi-functional proteins that form microfilaments in the cytoskeleton, and the thin filaments in muscle fibrils.

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.

Apoptosis, also known as programmed cell death, is a highly regulated form of cell death that occurs in multicellular organisms.

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 microtubule is a microscopic tubular structure found in the cytoplasm of almost all eukaryotic cells.

A synapse is a structure in the nervous system that allows neurons to communicate with each other.

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.