In this blog post, we will look at the role of killer T cells in finding and eliminating virus-infected cells and their importance in the immune system.
Our bodies have a “natural healing” function. What does “natural healing” mean? “Natural healing” means that our bodies have an immune system that can fight off viruses (antigens) without outside help. This is one of the survival mechanisms that humans have developed over many years of evolution, and it is an important defense system that protects and maintains the body from external threats. Without the immune system, we would be threatened by the countless pathogens we encounter every day.
More precisely, the immune system finds virus-infected cells in various ways and eliminates the viruses. In this process, the immune system responds quickly through the cooperation of various types of immune cells and proteins. Among the cells involved in this immune system, there are some that play a very important role. These are called killer T cells, which directly find and eliminate virus-infected cells. Killer T cells are like guardians that protect our bodies.
Killer T cells are a type of lymphocyte that patrols the body by traveling through the blood and lymphatic fluid. In addition to killer T cells, there are also helper T cells and B cells. When a virus invades the body, helper T cells activate B cells to produce antibodies, which then destroy the virus. The antibodies produced by B cells play an important role in quickly targeting and eliminating specific viruses and bacteria. Antibodies bind to specific proteins on the surface of viruses, preventing them from invading other cells or neutralizing them so that other immune cells in the body can easily eliminate them. This process clearly demonstrates how the immune system responds to infection.
Killer T cells, on the other hand, attack infected cells directly. Killer T cells check each cell, like police officers conducting a drunk driving checkpoint on a road, to find cells infected with viruses. During this process, cells infected with viruses are detected by killer T cells and killed. So how do killer T cells destroy virus-infected cells?
The first to start working in the immune system is the major histocompatibility complex (MHC) on the cell surface. MHC is a protein molecule shaped like a crab’s claw that pulls protein fragments inside the cell to the cell surface. Let’s take a closer look at this process. Originally, most of the proteins in a cell are self-proteins, but once a cell is infected with a virus, viral proteins that did not exist before are created inside the cell. These self-proteins and viral proteins are broken down into peptide fragments by protein-degrading enzymes, float around inside the cell, and then bind to MHC and are delivered to the cell surface. Peptides are organic substances that are structurally similar to protein molecules but smaller.
This time, killer T cells come into action. Killer T cells determine whether a cell is infected with a virus by recognizing the structure formed by the MHC and peptide fragments that have come out of the cell through the “TCR (T cell receptor)” on their surface. If the peptide bound to MHC is from the cell itself, the T cell recognizes the cell as normal and passes it by. However, if the peptide bound to MHC is from a virus, the T cell activates and sends proteins that attack the cell into the infected cell. Cells attacked by T cells soon die, and the viruses inside them also die.
Even now, abnormal cell division and viral infections continue to occur throughout our bodies. However, as long as the mechanism by which killer T cells in our bodies find and destroy diseased cells is functioning normally, we can maintain good health. In this way, the immune system is the guardian of our bodies. It is also a good example of how our bodies are organically structured. This is not a simple mechanical reaction, but part of a complex life system in which countless cells and molecules work together organically to maintain the body’s balance and keep us healthy.
