What are blood cells involved in immunity?

There are several types of blood cells involved in the immune response:

1. Neutrophils: Neutrophils are the most abundant type of white blood cell and are crucial for the body's first line of defense against infection. They are phagocytic cells, meaning they engulf and destroy foreign particles, including bacteria, viruses, and damaged tissues.

2. Macrophages: Macrophages are large phagocytic cells located in various tissues throughout the body. They are derived from monocytes, which leave the bloodstream and differentiate into macrophages upon entering tissues. Macrophages play a critical role in removing cellular debris, foreign substances, and microorganisms.

3. Eosinophils: Eosinophils are involved in defending against parasitic infections and allergic reactions. They are particularly effective in destroying parasites using toxic chemicals stored in their granules.

4. Basophils: Basophils are the least common type of white blood cell and are associated with allergic responses. They release histamine and other inflammatory mediators upon activation, leading to symptoms such as sneezing, runny nose, and watery eyes.

5. Dendritic Cells: Dendritic cells are essential for the initiation and regulation of immune responses. They capture and process antigens (foreign molecules) and present them to immune cells like T cells, triggering an immune response.

6. B Cells: B cells are lymphocytes that produce antibodies. Antibodies bind to specific antigens, marking them for destruction by other immune cells. B cells differentiate into plasma cells upon activation, which secrete large amounts of antibodies.

7. T Cells: T cells are lymphocytes involved in cell-mediated immunity. They recognize and destroy infected or cancerous cells directly. Different types of T cells include cytotoxic T cells (which kill target cells), helper T cells (which assist in activating other immune cells), and regulatory T cells (which help control immune responses).

These blood cells work together to protect the body from infections, diseases, and foreign substances, ensuring proper immune function and overall health.