![]() Coughing and sneezing rids us of countless pathogens every day. A fever helps, as many bacteria will die at temperatures higher than normal body temperature. By increasing blood flow to the area, more white blood cells arrive to destroy the intruders. The first step after PAMP or DAMP recognition is the inflammatory reaction. A single pattern recognition receptor can recognize both pathogen- and damage-associated patterns. Many types of cells, including dendritic cells, have pattern recognition receptors (PRRs). ![]() Pathogen-associated molecular pattern signaling The macrophage catches and digests the bacteria (phagocytosis). Cytokines tell other cells that an attack is underway. Upon detection, the macrophage then secretes cytokines in response. The macrophage has receptors for the LPS pattern that detect the PAMPS. The following image shows the invasion of pink antigen bacteria with PAMPs in the form of LPS (lipopolysaccharide) on their outer membranes. Our pwn cells, when damaged, dying or dead, present with DAMPs (damage-associated molecular patterns). All microbes have similar general patterns of molecules known as PAMPs (pathogen-associated molecular patterns) on their outer surfaces. If an antigen enters the body and survives despite these anatomical barriers, the next phase in the innate immune system defense mechanism takes over. These anatomical barriers are part of the innate immune system. These include skin, stomach acid, airway mucus, the blood-brain barrier, sweat, and tears. Most vertebrates have multiple protective barriers. Antigens range from viruses and bacteria to chemicals released from damaged cells when they are burned, scratched, starved of oxygen, or otherwise traumatized. The innate immune system is a nonspecific mode of protection that occurs before, at, or within a short time of antigen exposure. Antigens and antibodies Dendritic Cell Function: Innate Immune System Antibodies are a later stage of immunity that will be described further on. In the image, the orange antigens with many surface proteins have been detected by antibodies – the Y-shaped blue-green particles. This is because certain patterns of molecules on the antigen or on damaged cell membranes make them recognizable. The presence of an antigen – or its surface proteins – stimulates an immune response. Dendritic cells have an important function in the innate immune system where they carry out surveillance duties, looking for antigens in the form of endogenous toxins and exogenous foreign substances.
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