Natural Killer Cell Activity

Natural killer cells are a type of white blood cell.

The immune system includes different types of cells that work to protect the body from harmful threats. Some cells are designed to kill off harmful organisms, while others store information on past encounters with potentially threatening organisms. Natural killer cells are the body's first line of defense when a potential threat is detected.

Identification

Natural killer cells--also known as NK cells--are a type of lymphocyte, or white blood cell, within the immune system. According to LiveScience, a science-health-technology resource site, NK cells make up 10 to 15 percent of the total number of lymphocytes in the body. These cells are "cytotoxic," meaning they contain poisons designed to kill off other cells, according to ScienceDaily, a science information resource site. Natural killer cells are manufactured by bone marrow cells continuously.

Function

The poisonous materials contained inside natural killer cells are designed to contain, or isolate, a nearby cell when a viral or bacterial threat is detected, according to ScienceDaily. NK cells contain perforin and proteases, which are protein materials designed to paralyze nearby cells. NK cells do this by opening up the cell and injecting perforin and proteases inside it. These chemicals work to eat away at the cell's structure, which give T-cell lymphocytes time to reach the affected area. NK cells also secrete chemicals that let the immune system know that a threat is present.

Effects

Natural killer cells flow through the blood and lymphatic fluids, which enables them to be present in every area of the body. NK cells act as an early response system to perceived bacterial or viral threats. Cells that are under attack secrete chemicals known as interferons. When interferons are secreted, this activates NK cell activities. Interferons also alert the entire immune system to potential threats in the body. In effect, a body that has a low number of NK cells may be susceptible to infectious, or disease-causing, agents.

Apoptosis

Apoptosis is a type of preprogrammed cell death that occurs when a cell begins to develop abnormal characteristics. Natural killer cells work to induce apoptosis as they inject poisonous materials into affected cells, according to Community College of Baltimore County. As the poisons spread through the cells, it begins to breakdown cell DNA-RNA production processes. In doing so, the cell is unable to carry out normal processes like metabolism and routine cell repair activities.

T-Cells

Natural killer cells help to regulate the number of T-cells that access an affected area, according to Medical News Today. If too many T-cells attack an affected area, the risk of harm to nearby healthy cells increases. As T-cells are designed to kill off an infectious agent, an overabundance of them in any one area may result in the death of normal healthy cells. Unlike natural killer cells, T-cells have to adapt to new invading organisms before they're capable of killing them off. In this regard, T-cells are considered the body's second line of defense against potential threats.

References

• ScienceDaily: Natural Killer Cell
• LiveScience: Natural Body Guards: How Your Killer Cells Get Motivated
• Medical New Today: Natural Killer Cells Keep Immune System in Balance
• Reproductive and Cardiovascular Disease Research Group: Apoptosis
• Community College of Baltimore County: The Adaptive Immune System

Resources

• Immune System