Immunology

The human immune system is extraordinarily complex — comprising innate immunity (fast, non-specific responses) and adaptive immunity (slow, highly specific responses to particular pathogens, with immunological memory). It involves approximately 10 types of white blood cells (neutrophils, macrophages, dendritic cells, B cells, T cells, NK cells, and more), complement proteins, antibodies, and cytokine signaling networks. The adaptive immune system can generate antibodies to approximately 10^14 (100 trillion) different antigens — it recognizes almost anything it might encounter. B cells produce antibodies; T cells either kill infected cells (cytotoxic) or coordinate immune responses (helper). Autoimmune diseases occur when the immune system attacks the body's own cells. Immunotherapy has revolutionized cancer treatment by removing the 'brakes' that cancer cells apply to immune responses.