The humoral innate immune system consists of naturally occurring antibodies, pentraxins, the complement system, and the contact system. These components defend the body from various pathogens. Naturally occurring antibodies and pentraxins recognize and neutralize pathogens. The complement system enhances immune responses, while the contact system aids in immune cell recruitment and pathogen clearance.

The immune system employs two distinct strategies to defend against pathogens: humoral and cell-mediated immunity. Humoral immunity, mediated by B lymphocytes and antibodies, is effective against extracellular threats like bacteria and viruses in bodily fluids. Cell-mediated immunity, involving T lymphocytes, targets intracellular pathogens and cancerous cells, providing comprehensive defense.

Active immunity arises when the body's immune system responds to direct exposure to pathogens or vaccination, resulting in production of antibodies and formation of memory cells for long-term protection. Conversely, passive immunity, obtained either naturally or artificially through transfer of pre-formed antibodies, offers immediate but temporary protection without the formation of memory cells.