How The Immune System ACTUALLY Works – IMMUNE

Neutrophils deploy broadly toxic chemicals and destructive tactics (including NET release) that don’t discriminate well between microbes and host tissue, so their activity can cause collateral damage during infection.

Long-term immunity emerges because a small fraction of activated T and B cells survive as memory cells that remain in tissues or keep making low-level antibodies, so re-exposure triggers a faster, stronger response.

Antibodies bind microbes and clump them together, which prevents their movement or function and makes them easy targets for phagocytes to clear.

After activation and clonal expansion, each B cell clone secretes thousands of antibody molecules per second, which quickly saturate the infection site and neutralize pathogens by binding them.

Adaptive immunity is relatively slow because the rare T and B cells that recognize a pathogen must undergo repeated clonal divisions to produce enough effector cells, delaying the full-strength response.

The immune system keeps billions of distinct helper T cells—each with a unique receptor—so when a new pathogen appears there's likely already a T cell able to recognize its specific molecular pattern.

Dendritic cells sample microbes, break them into fragments and display those pieces on their surface, then travel to lymph nodes to find helper T cells with matching receptors and thereby activate a specific adaptive response.

Inflammation makes blood vessels leak fluid into tissue, which delivers complement proteins that assemble on bacterial membranes and punch holes to stun and kill microbes.