Which type of cells are the first responders to sites of infection?

Neutrophils are considered the first responders to sites of infection due to their rapid mobilization and response to inflammatory signals. When there is an infection or tissue injury, neutrophils are quickly recruited to the affected area from the bloodstream, where they play a crucial role in the initial immune response. They excel at phagocytosing pathogens, such as bacteria and fungi, and releasing antimicrobial substances that help to kill and digest these invaders.

The role of neutrophils is particularly important in acute immune responses, where their fast action can limit the spread of infection and begin the healing process. This function distinguishes them from other immune cells, which typically mobilize later in the immune response. For instance, macrophages, while also important for phagocytosis and orchestrating the immune response, typically arrive after neutrophils. Monocytes, which can differentiate into macrophages, and B cells, which are primarily involved in the adaptive immune response, take more time to be activated and respond. This is why neutrophils are recognized as the key first responders in the body’s defense against infection.