Immunity refers to the ability of an organism to resist or defend itself against harmful pathogens such as bacteria, viruses, or parasites. It is a complex system involving components, including white blood cells, antibodies, and specialized organs. The immune system is our body’s first defense against disease and infection. When it is compromised, our vulnerability to infections increases dramatically. Infections can be fatal, particularly those caused by severe pathogens such as viruses or bacteria. Immunity is a significant factor in maintaining health and our ability to survive under challenging conditions.
Innate immunity is our bodiesbodies’ natural response upon first recognizing a microorganism or foreign cell. This is the body’s initial defense and is non-specific and temporary. It is also called “natural” immunity because it is present from birth. This first line of defense is a combination of physical and biochemical defenses. It includes the skin (which acts as a barrier) and a host of other specialized cells present throughout our bodies.
Specific defenses against pathogens result from our immune system producing specialized cells called lymphocytes and antibodies. These specialized cells attack pathogens by looking at the surface markers on the microorganism, identifying them as not belonging to our body, and then producing antibodies against these antigens. The antibodies stick to the antigens, making it easier for other cells to recognize and destroy the pathogens.
These cells are often found in specialized tissues, including the spleen and bone marrow. These cells can also destroy cancers and certain other specialized types of cells and remove old or damaged blood vessels. They can also kill tumors and viruses by phagocytosing them – a process in which the cell engulfs and digests them. They can also activate a group of proteins that help kill bacteria, viruses, or infected cells – this is known as a complement.
Other white cells, such as granulocytes (neutrophils, basophils, and eosinophils), are also part of the innate immune system. They are the body’s ‘first responders’ and circulate in the blood and reside within tissues to look for potential problems – they can also release toxins into the tissue to cause damage. They can also produce antibodies and signal to other immune cells that an invading pathogen has been recognized.
B cells are another type of specialized cell that can produce antibodies. They can also recognize antigens by their surface markers, but they can bind to them more quickly when they have been ‘taught’ by the cells that recognized them previously – this is known as antibody memory.
Many things, including some medications, can compromise innate immunity. Some common drugs used in the treatment of cancer or to prevent transplant rejection can weaken the immune system temporarily. Acute illnesses like the flu, mono (mononucleosis), or measles can temporarily depress immune function. In addition, a poor diet or lack of exercise can also impair immune function. Nutrients such as vitamins, minerals, and the omega-3 fatty acids eicosapentaenoic acid and docosahexaenoic acid are needed to support immune function.