Introduction to Cells of the Immune System

The immune system is a complex network of cells, tissues, and organs that work together to protect the body from invading pathogens. These cells of immune system play a crucial role in the immune response by recognizing, attacking, and eliminating harmful invaders. In this study note, we will discuss the different types of cells that make up the immune system, their functions, and their interactions with each other.

White Blood Cells (Leukocytes)

• White blood cells, also known as leukocytes, are the primary cells of the immune system.
• They are divided into two main types: granulocytes and agranulocytes.

Granulocytes

• Granulocytes are a type of white blood cell that contains granules in their cytoplasm.
• They include neutrophils, eosinophils, and basophils.
• Neutrophils are the most common type of granulocyte and are responsible for phagocytosis and the production of enzymes that kill bacteria and fungi.
• Eosinophils are involved in the immune response to parasites and allergens.
• Basophils are involved in the production of inflammatory mediators and the immune response to allergens.

Agranulocytes

• Agranulocytes are a type of white blood cell that do not contain granules in their cytoplasm.
• They include lymphocytes and monocytes.
• Lymphocytes are responsible for the adaptive immune response and include T cells and B cells.
• Monocytes are involved in the innate immune response and differentiate into macrophages and dendritic cells.

T cells

• T cells, also known as T lymphocytes, are a type of lymphocyte that play a crucial role in the adaptive immune response.
• They include CD4+ T cells and CD8+ T cells.
• CD4+ T cells, also known as helper T cells, are involved in the regulation of the immune response and the activation of other cells.
• CD8+ T cells, also known as cytotoxic T cells, are responsible for the direct killing of infected cells.

B cells

• B cells, also known as B lymphocytes, are a type of lymphocyte that produce antibodies as part of the adaptive immune response.
• They also differentiate into plasma cells, which produce and secrete antibodies.

Macrophages

• Macrophages are a type of white blood cell that are involved in the innate immune response and the phagocytosis of pathogens and other foreign particles.
• They also play a role in the activation and regulation of the immune response by releasing cytokines and other signaling molecules.

Dendritic Cells

• Dendritic cells are a type of white blood cell that are involved in the innate immune response and the initiation of the adaptive immune response.
• They act as professional antigen-presenting cells, capturing and processing antigens and presenting them to T cells to initiate an immune response.

Natural Killer cells

• Natural Killer (NK) cells are a type of agranulocyte that are involved in the innate immune response.
• They are responsible for the direct killing of infected and malignant cells through the release of cytotoxic granules.

Conclusion

The immune system is made up of a diverse range of cells that work together to protect the body from invading pathogens. These cells include white blood cells, such as granulocytes and agranulocytes, T cells, B cells, macrophages, dendritic cells, and natural killer cells. Each of these cells plays a specific role in the immune response and their interactions with each other are crucial for the effective functioning of the immune system.