In the study of the immune system, understanding the types of leukocytes, or white blood cells, is crucial. Agranulocytes are a key category of these cells, distinguished by the absence of visible cytoplasmic granules when viewed under a light microscope. The two primary types of agranulocytes are monocytes and lymphocytes.

Monocytes circulate in the bloodstream and have the unique ability to differentiate into macrophages or dendritic cells. Macrophages are essential for phagocytosis, where they engulf and digest pathogens, while dendritic cells play a critical role in antigen presentation, bridging innate and adaptive immunity.

Lymphocytes are further divided into B cells and T cells, both integral to adaptive immunity. B cells are responsible for producing antibodies that target specific antigens, while T cells are involved in cell-mediated immunity, helping to destroy infected host cells and coordinating the immune response. Additionally, natural killer (NK) cells, which are also classified as lymphocytes, contribute to innate immunity by targeting and destroying virally infected cells and tumor cells.

As we delve deeper into the immune system, we will explore the functions and mechanisms of these agranulocytes, particularly focusing on their roles in both adaptive and innate immunity. Understanding these cells is fundamental to grasping how the body defends itself against pathogens and maintains overall health.