True or False: Natural killer cells are part of the specific immune system.

Natural killer cells are indeed part of the innate immune system, rather than the specific (or adaptive) immune system. The innate immune system is the body’s first line of defense against pathogens, providing a rapid response to infections and a non-specific defense mechanism.

Natural killer cells play a crucial role in this system by recognizing and destroying virus-infected cells and tumor cells without the need for prior sensitization to a specific antigen. They can respond quickly to a wide range of potential threats, emphasizing their role in non-specific immunity.

In contrast, the specific or adaptive immune system involves lymphocytes such as B cells and T cells that require activation and often rely on previous exposure to specific pathogens to mount a targeted response. Thus, the classification of natural killer cells as part of the innate immune system reaffirms the distinction between these two major components of the immune response.