What is the primary function of the spleen in the immune system?

The primary function of the spleen in the immune system is to filter blood and produce immune responses. The spleen plays a crucial role in monitoring and responding to pathogens that enter the bloodstream. It contains immune cells, such as lymphocytes and macrophages, which help identify and eliminate foreign invaders, including bacteria and viruses.

When blood passes through the spleen, it is filtered to remove damaged or old red blood cells as well as debris and pathogens. The immune cells present in the spleen can quickly respond to these threats, producing antibodies and other substances that assist in the immune response, effectively protecting the body from infections.

The other options, although related to bodily functions, do not accurately represent the primary role of the spleen in the context of the immune system. Vacuuming blood, storing platelets, and regulating blood sugar are functions associated with different aspects of physiology rather than the immune response specifically managed by the spleen.