Innate immunity

Innate immunity is the first line of defense against harmful substances that enter the body. It is also known as natural immunity or genetic immunity. The innate immune system detects invaders known as pathogens and releases special cells that attack them. Innate immunity is present at birth, does not need to be learned, and can be very effective. The innate immune system does not identify what type of attack is present and reacts in much the same way regardless of the substance present. It is still an important and valuable part of protecting against disease and illness caused by foreign substances.

Overview

The immune system is the body’s way of protecting against diseases caused by pathogens. Pathogens are organisms such as viruses, bacteria, parasites, and fungi. The immune system also protects against the effects of toxins such as poisons.

Immunity works in two ways: through innate immunity and through adaptive immunity. The innate immune system is present at birth and is the first line of defense. The adaptive immune system is activated by the innate immune system. Also known as acquired immunity, the adaptive immune system develops and remembers a response to specific pathogens. Both innate and adaptive immunity are important to protect a person’s overall health.

Innate immunity is coded into a person’s genes and provides protection from illness beginning at birth. The innate immune system begins to work rapidly after exposure to a pathogen or toxin.

The innate immune response can come in the form of physical barriers, chemical barriers, or cellular defenses against the invading pathogen or toxin.

• Physical barriers such as skin, eyelashes, and the hairs inside the nose interfere with the ability of a pathogen or toxin to enter the body. The coughing reflex creates a physical barrier by expelling potentially harmful substances.
• Chemical barriers include tears and nasal secretions. They help wash pathogens or toxins from the body. Stomach acid is another chemical barrier; it kills many types of pathogens that enter through the mouth into the digestive system.
• White blood cells act as cellular defenses that directly identify, attack, and destroy pathogens. They include dendritic cells, mast cells, macrophages, neutrophils, basophils, and eosinophils. These cells, in turn, produce other cells that weaken or kill invading pathogens.

The innate immune system helps neutralize or kill pathogens and helps attract cellular defenses to the part of the body where they are most needed. It also triggers the acquired immune system to develop specialized cells called antibodies to attack the pathogens and helps the body eliminate dead cells as the immune system works. Innate immunity can develop a limited form of memory, called ‘trained immunity,’ allowing it to respond more strongly to repeated exposures.

The innate immune system is part of a healthy and efficient immune response to protect the body from illness. However, it can sometimes result in undesired responses. In some cases, the system will react to substances that are generally not harmful. When this unnecessary response is excessive, it results in allergies.

Bibliography

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