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How do phagocytes destroy invading microorganisms?

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Immune stimulation by activated helper T cells — immune system Stimulation of immune response by activated helper T cells. Activated by complex interaction with molecules on the surface of a macrophage or some other antigen-presenting cell, a helper T cell proliferates into two general subtypes, T_H1 and T_H2. These in turn stimulate the complex pathways of the cell-mediated immune response and the humoral immune response, respectively.

Phagocytes destroy invading microorganisms through a multi-step process known as phagocytosis.

First, the phagocyte must adhere to the target. If direct adhesion is not possible, the process is facilitated by opsonins—such as antibodies or complement proteins—which coat the bacteria to make them recognizable to the phagocyte.1

Once attached, the phagocyte extends its cytoplasm into pseudopods, flowing around the microorganism until it is completely engulfed. The ingested particle is then enclosed within a membrane-bound vacuole called a phagosome.21

To destroy the invader, the phagocyte utilizes lysosomes, which are membrane-enclosed sacs containing hydrolytic enzymes. These enzymes are secreted into the phagosome, where digestion takes place. This internal containment ensures that the phagocyte remains protected from the toxins or poisons potentially released by the bacteria during the digestive process.21