AAMC FL Practice Exam 2025 – The Comprehensive All-in-One Guide to Exam Success!

Cytotoxic T cells are a specific type of T lymphocyte (T cell) that play a crucial role in the immune system by directly killing infected cells, cancer cells, and sometimes foreign tissue. They are essential in controlling and eliminating threats to the body, such as viral infections and tumor cells. When cytotoxic T cells identify a target cell displaying foreign antigens on its surface, they engage with that cell and induce apoptosis (programmed cell death), effectively neutralizing the threat.

These cells are characterized by their expression of the CD8 co-receptor, which helps them recognize antigens presented by Major Histocompatibility Complex (MHC) classes I molecules found on nearly all nucleated cells. This interaction is vital for the cytotoxic function of T cells, allowing them to respond specifically to infected or abnormal cells.

The other types of immune cells mentioned in the other options serve different functions. For instance, B cells are the ones that produce antibodies, which help in the immunity against pathogens. Helper T cells activate other immune cells, enhancing the overall immune response, while certain immune cells, such as mast cells and basophils, are primarily involved in promoting inflammation as part of the body's response to injury or infection. Each of these functions is