Factors Affecting Our Immune System

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Why do people get sick? Why do some people have allergies while others don’t? Questions like these have long been unanswered in the medical science. Today, we know that all of these queries are attributed to our immune system. Before we discuss the knowledge that we have today, it is important to have a grasp on history of immune system as well.

History Facts

The field of Immunology started in the last quarter of the nineteenth century with scientist Elias Metchnikff’s (1845–1916) identification of phagocytic cells, which engulf and destroy invading pathogens. This laid the basis for innate immunity.

elias metchnikff

The earliest known reference to immunity was during the plague of Athens in 430 BC. Thucydides noted that people who had recovered from a previous bout of the disease could nurse the sick without contracting the illness a second time. This introduced a new field in medical sciences, now-called ‘immunology’; which brings us to our current topic of discussion.

Body’s Defenses

The immune system is a complex network of cells, tissues, organs, and the substances they produce (antibodies and hormones) that helps the body fight infections and other diseases. The immune system includes white blood cells that are lymphocytes, phagocytes, basophils, neutrophils and eosinophils; and organs and tissues of the lymphatic system, such as:

network of cells
  • Thymus
  • Spleen
  • Tonsils
  • Lymph nodes
  • Lymph vessels
  • Bone marrow

In sparing terms, the immune system is an acutely monitored system in body homeostasis that protects it from any external or internal harm.

This system works together to protect you from foreign invaders (bacteria, viruses, parasites, and fungi) and internal processes that mean to damage the body integrity and prevent it from functioning efficiently.

Immune system – how it works 

The immune system works with various integrated systems of the body and employs several different types of cells and tissues that work synergistically to bring about the normal processes. For this reasons, the normal functioning is greatly influenced by factors that may be internal or external or others. Some of these top factors are discussed below.

integrated system

Physiological factors 

Body immunity is sensitive to the smallest changes. Any change in bodily systems directly impacts the function of immune system.


Immune system is activated by stressors that tend to stimulate its activity. Normal circadian rhythms act to decrease the level of triggers and suppress the immunity. However, if a person has a busy schedule and consequently a disrupted sleep-wake cycle, the immune system in this case will be active and will respond to changes that it does not usually respond to. 


Stress, anxiety, insomnia and similar conditions trigger the release of the steroid hormone i.e. ‘cortisol’. Cortisol has a direct influence on the immune system. When the level of cortisol increases persistently, they can desensitize the immune system and hence make it ‘resistant’ to any necessary changes e.g. inflammation and infection.

the biggest trigger


Nutrition is important in keeping the body immunity intact. Diet provides sufficient Vitamins like B, C, and D, A, B12 and minerals like zinc, calcium and magnesium. All of these elements are crucial for normal T-cell activity. Any discrepancy in dietary supplements can impair immune responses and thus increase your risk of catching an infection.


Hygiene is the most important natural determinant of immunity. Lack of hygiene makes an individual more prone to infections, diseases and other disorders that act to activate immune system. Immune system activation that is initiated by impaired hygiene or contamination usually presents with fever and other symptoms. 

Environmental factors

Environmental stressors are the most significant factors that impact the immune system. They can cause damage to immunity at gross, macro and micro-molecular levels and can even damage the immune system genetics of the body.


We as human beings encounter infections by oblivion. These infectious causes can be bacterial, viral, amoebic or fungal depending upon the source and the mechanism by which they affect the immune system. Common infections that affect the immunity are sore throat, influenza, mumps and measles, chicken pox, cholera and typhoid. All of these make the body sensitive to antigens. The antigens are then neutralized by cytotoxic T-cells of the immune system. a side effect of this reaction is the release of pyrogens that cause pyrexia; commonly known as ‘Fever’.


Trauma usually causes the rupture of intact skin and membranes and hence exposes the body to an enormous amount of pathogens. It is, thus, the most potent activator of immune system.


Carcinogenic Toxins

UV-rays, X-rays, Radioactive radiation and other chemical toxins like inorganic acids can displace the human body’s ability to detect foreign bodies. Further, they distort the normal production of immune cells (T and B-cells) so that any response to damage is also inhibited. This is the most dangerous type of damage to immune system.

Pathological factors

Our immune system is prone to threats from within as well. Keep reading to know more about these peculiar ones.

Overactive Immunity 

At times, body immunity is overly sensitive to changes in the external environment. There is no clear mechanism known as to why this happens. In this case, any stimulus produces a greater than normal response to cellular injury. This is explained by the presence of allergies in some people. Common allergies include asthma, eczema, hay-fever, allergic rhinitis etc.

Immune Deficiency

Some pathogens like HPV, CMV, and Syphilis and commonly known HIV can make the body immunity inefficient. The mechanism involves an attack on the immune cell itself so that their destruction is perpetuated. This puts the body at open risk for a myriad of infections and diseases. People who have immune deficiency have poor life prognosis in general.

inefficient immunity


It is said to be present when immune cells consider the normal healthy cells as foreign and launch an attack causing body to go into a complete shutdown regarding metabolic, hormonal and other systems. Commonly known autoimmunity diseases are SCID, SLE, Graves disease and Addison disease etc.


Our immune system is extremely important in neutralizing any damage that means to harm the body. It is, thus, important to boost the immunity so that it keeps protecting us. How to boost the immune system? 

Take good care of hygiene, get a good night’s sleep, supplement your body when necessary and avoid environmental exposure to substances that tend to negatively impact the immune system. Few effective ways to boost your immunity are given in this article.

To know more about the factors affecting your immune system, watch the video below:

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