Which group of cells in the immune system is directly involved in fighting infections?

B cells are a crucial component of the immune system that plays a direct role in fighting infections. These specialized cells are a type of lymphocyte, which is a category of white blood cells. When B cells encounter pathogens such as bacteria or viruses, they respond by producing antibodies, which are proteins that recognize and bind to specific antigens on the pathogens. This binding marks the pathogens for destruction by other immune cells and neutralizes their ability to cause harm.

The activation of B cells typically requires interaction with helper T cells, which provide necessary signals that enhance the B cells' ability to produce antibodies. Once activated, B cells can also undergo a process called clonal expansion, leading to the formation of a large population of identical cells that can effectively target the same invader.

This ability to produce specific antibodies makes B cells essential in the adaptive immune response, which provides long-lasting protection against pathogens the body has previously encountered. Additionally, some B cells differentiate into memory B cells, which help the body respond more rapidly upon subsequent infections by the same pathogen.