How do blood cells contribute to immune responses?

Blood cells contribute to immune responses by identifying, attacking, and eliminating pathogens and foreign substances in the body.

Blood cells, specifically white blood cells, play a crucial role in the body's immune response. They are the body's primary defence mechanism against infections and diseases. There are several types of white blood cells, each with a unique role in the immune response.

Neutrophils, the most abundant type of white blood cells, are the first to arrive at the site of an infection. They engulf and destroy bacteria and fungi, a process known as phagocytosis. Eosinophils are responsible for combating parasites and are also involved in allergic reactions. Basophils release histamine during an allergic reaction, causing inflammation that helps other white blood cells reach the affected area.

Lymphocytes, another type of white blood cell, are further divided into B cells and T cells. B cells produce antibodies, proteins that recognise and bind to specific antigens on the surface of pathogens. This binding signals other immune cells to destroy the pathogen. T cells, on the other hand, can directly kill infected cells. Helper T cells stimulate B cells to produce antibodies and cytotoxic T cells to kill infected cells, while regulatory T cells prevent the immune system from attacking the body's own cells.

Monocytes, which transform into macrophages when they reach the body's tissues, also perform phagocytosis. They are particularly effective at eliminating bacteria and dead or damaged cells. They also present antigens to T cells, triggering an immune response.

Platelets, although not traditionally considered part of the immune system, also contribute to immune responses. They can bind to pathogens, slowing their spread, and release substances that attract white blood cells to the site of an infection.

In summary, blood cells are integral to the body's immune responses. They identify, attack, and eliminate pathogens, helping to protect the body from infections and diseases.