Which theory describes the immunity that involves direct contact between macrophages and invading antigens?

The theory that accurately describes the immunity involving direct contact between macrophages and invading antigens is the Theory of Cell-Mediated Immunity. This type of immunity is primarily orchestrated by T cells and involves the activation of immune cells, including macrophages, to target and eliminate intracellular pathogens, tumor cells, and infected cells through direct interaction.

In cell-mediated immunity, macrophages play a crucial role not only in recognizing and phagocytizing antigens but also in presenting these antigens to T cells, which enhances the immune response. This direct contact allows for a more robust and targeted response against threats that may be hiding within cells, unlike other immunity types that rely mostly on antibodies produced by B cells circulating in the body.

This response is essential for dealing with infections that cannot be effectively eliminated by antibodies alone, such as viral infections and certain intracellular bacteria. Therefore, understanding cell-mediated immunity is vital for comprehending how the body defends itself against various pathogens at the cellular level.