What proteins are fundamental to the immune system?

Fundamental proteins in the immune system include antibodies, which are produced by B cells and help neutralize pathogens, and cytokines, which are signaling molecules that mediate communication between immune cells. Additionally, complement proteins play a crucial role in marking pathogens for destruction and enhancing the immune response. Other important proteins include major histocompatibility complex (MHC) molecules, which present antigens to T cells, activating adaptive immunity. Together, these proteins coordinate the body's defense against infections and diseases.