Acquired continued

B cells make antibodies (a y-shaped protein that neutralises pathogens) Each antigen stimulates production of a single and specific antibody. The B cell recognizes the different antigen on the surface of a macrophage When a B cell meets and interacts with a specific antigen, the B cell becomes metabolically active and begins to divide.

Plasma cells – specialised antibody factory. After 5 to 8 days it can produce thousands of antibody molecules per second. Memory cells – long-lived B cells that remain in lymph tissues and are responsible for the immunity that arises following infection or vaccination. The response of memory B cells is faster and more sensitive

To respond to most antigens, B cells need the assistance of helper T cells (TH cells). T-cells contribute to your immune defenses in two major ways. Some help regulate workings of the overall immune response, while others are cytotoxic and directly contact infected cells and destroy them.

Four main types of T cells: – Helper T Cells – Killer T cells – Suppressor T cells – Memory T cells

Recognise antigens on the surface of white blood cells, particularly macrophages. * Secrete interferon and cytokines which stimulate B cells and cytotoxic T-cells (killer T-cells).

Also called cytotoxic T cells. Destroy abnormal body cells, e.g. virus infected or cancer cells. Stimulated by cytokines. Release perforin which forms pores in target cells – this allows water and ions in and leads to lysis of the target cell. Cytotoxic T cells need to recognize a specific antigen bound to self-MHC markers.

Suppressor T-cells or regulatory T-cells control the immune system when the antigen/pathogen has been destroyed. This prevents the immune system from damaging its own cells

Survive a long time and can give lifelong immunity from infection. Can stimulate memory B cells to produce antibodies. Can trigger production of killer T cells.

Both B cells and T cells carry customized receptor molecules that allow them to recognize and respond to their specific targets

Cytokines are the chief communication signals of your T cells. Cytokines include interleukins, growth factors, and interferons. Lymphocytes, including both T-cells and B-cells, secrete cytokines. Many of these cytokines are also known as interleukins because they serve as a messenger between white cells, or leukocytes. Interferons are naturally occurring cytokines that may boost the immune system’s ability to recognize cancer as a foreign invader.