Elements of the Immune System

Mature T and B lymphocytes gather in the lymph nodes, spleen, and other lymphatic tissues, where they help filter the lymph of bacteria, viruses, tumor cells, and any other substances they recognize as foreign on a molecular level.

When macrophages are unable to eliminate invading bacteria during the inflammatory response, T and B lymphocytes are activated to mount a defense. Helper T lymphocytes release cytokines that stimulate the proliferation of cytotoxic T cells and natural killer cells.

This process leads to the formation of a robust army of immune cells specifically geared to destroy infected body cells. Activated B lymphocytes differentiate into plasma cells, which produce large quantities of antibodies—protective proteins that target pathogens remaining in the bloodstream or tissues.

Additionally, memory T and B cells are generated, remaining in the bloodstream to provide a rapid immune response if the same pathogen is encountered again, enabling a faster and more efficient defense than the initial immune reaction.