The immune system writes molecular wanted posters. An antibody is a Y-shaped protein produced by B cells that binds specifically to a foreign molecule, marking it for destruction or neutralizing its function.

Each antibody recognizes a particular epitope. Binding can block toxins or viral entry, activate complement, or flag pathogens for phagocytosis. Memory B cells retain the ability to produce the same antibody rapidly on re-exposure, forming the basis of humoral immunity and of vaccination.

Laboratory medicine exploits antibodies in diagnostic tests and as therapeutic drugs. Monoclonal antibodies can now target cancer cells, inflammatory cytokines, or specific viruses with high precision. Measuring antibody levels also reveals past infection or vaccine response.

• Y-shaped protein that binds specific foreign molecules
• Produced by B cells after antigen exposure
• Neutralizes pathogens and marks them for clearance
• Used in diagnostics and targeted therapies