Weak immune system

Weak immunity is the inability to fight infections or overcome illnesses that others around us can avoid or recover from quickly.

Since weak immunity is a lack/absence of something, let’s start with what should be there but is missing in some form or aspect. Consider how the immune system fights an infection:

• A pathogen/allergen/toxin enters the body. In 0-4 hours, the innate immune system recognises there’s something foreign inside the body and triggers inflammation to stop the infection from spreading. It also uses cytokines (proteins that the immune cells use to talk to each other) to call for help.
• Phagocytes, also part of the innate immune system, come into play. Phagocytes such as neutrophils are always making the rounds of the body via the bloodstream. Now, they enter the tissue where the infection is. Next, they call in the dendritic cells—also a type of phagocytes—to gobble the pathogen/allergen and break it down to its basic protein form.
• In case the infection is bacterial, the complement immune system kicks in to help the phagocytes mark and eat the bacteria or break through the bacteria’s cell wall. The complement system also releases histamines when an allergen enters the body. In the case of a viral infection, interferons mediate inflammation and trigger the next steps.
• Phagocytes—specifically, dendritic cells—then “present” these antigen proteins they’ve broken down in an earlier step, to the body’s adaptive immune system through the major histocompatibility complexes on their surfaces. The site of this presentation is the lymph nodes. The dendritic cells also release a protein (B7 protein) to confirm that there’s a need for an antigen-specific immune response.
• Next, it is the turn of T lymphocytes (T-cells) to respond. The naive T helper cells then quickly figure out whether the situation merits cell-mediated immunity or activation of B cells which can make antibodies. Both responses try to neutralize the antigen.

If any of these stages is unsuccessful for any reason or if the pathogen/allergen turns out to be stronger than the immune system, we get an infection.

Weak immunity is an inability to mount an appropriate immune response again and again—people with weak immunity put up an underwhelming response in situations where the immune response should be more robust, and therefore end up with frequent infections.

Weak immunity is distinct from immune system dysfunctions where the body puts up an overexuberant response, such as during a cytokine storm, or where it misdirects its response, as in an autoimmune disease such as psoriasis, lupus or Guillain-Barre syndrome.

Weak immunity could be temporary or lifelong. For example, someone with the flu or mononucleosis (Epstein-Barr virus or the kissing disease) would have weak immunity while they are recovering from these infections. Some medicines and therapies can also suppress immunity—for example, chemotherapy weakens the immune system.

People may be born with a weak immunity (there are over 150 primary immunodeficiency diseases), or they could develop it later in life. For example, people with HIV/AIDS (acquired immunodeficiency syndrome) are immunocompromised.

The immune system is complex, with lots of fail-safes and redundancies built in. Still, some people may be born with a weak immunity (primary immunodeficiency) or develop health conditions that weaken the immune system (immunocompromised). For example, cancer cells can weaken the immune response against them. Another example: People with HIV/AIDS have severely compromised immune systems. Indeed one in three people with HIV die of tuberculosis, an infection that takes advantage of the patients’ weakened immune system (opportunist infection).

The following are some common signs of a weak immune system:

• Falling sick more often than others: People with a weak immune system catch infections more readily. Pneumonia (infection-linked build-up of fluid in the lungs), meningitis (inflammation in a part of the brain called meninges), bronchitis (inflammation of the airways of the lungs or bronchi), ear infections and skin infections are just some of the infections that people with weak immunity may be prone to. People with a weak immune system could also get opportunistic infections that other people may be better protected against.
• Being sick for longer: People with a weak immune system are also likely to be sick for longer when they do contract an infection or illness. This also wound healing, which can be slow in people with low immunity.
• Some other health conditions linked with weak immunity are:
  • Autoimmune diseases: Where the immune system dysfunctions and starts attacking healthy cells in the body
  • Blood disorders like haemolytic anaemia, sickle cell disease and thalassemia (read more: Coombs test and thalassemia FAQs)
  • Inflammation in internal organs
  • Gastrointestinal problems: Gut-associated lymphoid tissue (GALT) constitutes a large part of our immune system. So people with weak immunity may also experience digestion- and gut-related issues like loss of appetite, diarrhoea, and stomach cramps
• Weak immunity and repeated infections can also impair growth in children and cause developmental delays.

Weak immunity could be the result of a few broad factors:

• Genetic or hereditary conditions: Some people may be born with a poor immune system because of a fault in their genes or because of a family history of primary immunodeficiency or severe combined immunodeficiency (SCID). (Read more: What is gene therapy)
• Disease or infection: The immune system may be affected by:
  • Some infections, like HIV and measles, which can affect the immune system either chronically or temporarily.
  • Leukopenia is a condition in which the patient’s blood does not have enough white blood cells. It can happen for several reasons, including:
    • Birth defects like Kostmann syndrome and WHIM syndrome (warts, hypogammaglobulinemia, immunodeficiency, myelokathexis)
    • Autoimmune disorders like lupus
    • Nutritional deficiencies like zinc deficiency, copper deficiency, folate deficiency, vitamin B12 deficiency (Read more: Wilson's disease)
    • Blood cancer (leukaemia) or any cancer that affects the bone marrow
    • Blood disorders like aplastic anaemia
    • Mental health conditions like anxiety and depression, too, hurt immunity.
    • Research shows chronic loneliness also weakens immunity and makes people susceptible to illnesses.
    • Chronic illnesses like diabetes affect immunity and make patients more susceptible to infections.
    • Recurring infections can weaken the immune system.
• Some medicines and therapies: We know that chemotherapy weakens the immunity for some time. Several medicines work by suppressing the immune system and reducing inflammation. Some commonly used medicines that do this include:
  • Corticosteroids that are used to treat arthritis, asthma, allergies, among other conditions.
  • TNF inhibitors, which are used to treat autoimmune diseases like rheumatoid arthritis and inflammatory bowel disease.
  • Immunosuppressants that are given to organ transplant recipients, to avoid organ rejection and graft versus host disease (GvHD). GvHD is a condition in which the immune cells in the healthy donor organ see the recipient’s body tissues as foreign, and attacks them.
  • Antibiotics can indiscriminately stop or kill bacteria, even the good bacteria in our mouth, gut and vagina. When there’s an imbalance in the natural microbiome of the body, it can make us more prone to certain infections. For example, an imbalance in gut bacteria can make people more susceptible to C. difficile infection
• Lifestyle: Inadequate sleep (less than seven to eight hours daily for adults), lack of physical exercise, fatigue, high levels of stress, smoking, alcohol use, malnutrition and nutritional deficiencies can affect immunity negatively.
• Advancing age: As we get older, our immune system becomes weaker. Research shows that this occurs because our T-cells, the immune cells responsible for identifying pathogens and calling the B cells to make antibodies, don’t work as well when we get older. Scientists say that most vaccines also don’t work as well in older people for this reason.
• Skin damage: Our skin provides a physical barrier to the entry of foreign objects, including disease-causing pathogens. Additionally, it plays a role in fighting against infections, some autoimmune conditions and allergies. The skin also provides some tumour immunity. The following immune cells can be found in the skin: Langerhans cells, dermal dendritic cells, macrophages, mast cells, natural killer (NK) cells and memory T cells. From an open wound to atopic contact dermatitis and burns, any condition that renders the skin weaker also affects the immune function of the skin.
• Pregnancy: Research shows that during pregnancy, the maternal immune system changes several times to protect and sustain the pregnancy. A fallout of this is that pregnant women become more prone to infections like urinary tract infections. However, this is a temporary loss and women typically recover their normal immune function after delivery.

Someone with a weak immune system would get infections and illnesses more often than their peers. And they could be more severely affected by the infection and be sick for longer. People with weakened immunity may also be more susceptible to a range of health issues like gastrointestinal problems.

If you suspect that you or your child have the symptoms of a weak immune system, visit a doctor. The doctor will begin by asking you about your medical history, and about any family history of immune dysfunction.

Next, he or she may advise some tests. A blood test may be advised to check for the presence of adequate immune cells. A healthy individual would have 5,000-10,000 white blood cells (WBCs) per millilitre of blood. Fewer WBCs would indicate a problem.

The doctor may also advise an immunoglobulin test to check if your body is making antibodies as it should.

Our immune system may be weak for a short duration or throughout life. It can also be weak for many reasons from smoking to primary immunodeficiency (a congenital condition). The fix for weak immunity, then, is linked with the cause. Some general rules of thumb to improve immunity are:

• Quit smoking and chewing tobacco: World Health Organization data show that quitting tobacco has positive and cascading effects on health within minutes. Leaving tobacco improves oral health, blood pressure, heart health, and of course lung health. It also improves the overall immune system.
• Eat a balanced diet: Deficiency of important vitamins and minerals can weaken our immune system. Make sure your meals are planned to include nutrients and to maximize their absorption in the body. For example, research shows that adding amchur (dry mango powder) or citric acid to grains increases the bioavailability of the zinc and iron in them. If you have a condition such as malabsorption or if you are getting on in years, talk to your doctor about a suitable vitamin B12 supplement for you.
• Prevent and fight infections: People with a weak immune system need to fight infections quickly and aggressively. If you or someone in your family has weak immunity, stay in constant touch with your general physician and ask their advice when you feel like you or the family member with the weak immunity may be coming down with something. Do not ignore signs like fever and inflammation. And always visit your GP when the medicine course they prescribed gets over—this will allow the doctor to see whether the infection is gone or if you need to continue treatment for longer.
• Get adequate sleep: Research has shown that inadequate sleep disturbs the hormonal balance and weakens immunity. Adults need seven to eight hours of sleep daily.
• Maintain good hygiene: This includes using the right way to wash hands to avoid infection, maintaining respiratory hygiene (by sneezing into the hook of your arm, for example).
• Avoid sick people: If you have a weakened immune system, avoid contact with people who have something contagious—even if it is something commonplace like the flu.

Treatment options for people with very weak immunity include:

• Stem cell transplant: In cases where the immunodeficiency (lack of immunity) is serious—potentially life-threatening—a doctor may advise you to get a stem cell transplant. This treatment is often used after cancer therapies like chemotherapy, to restore the body’s immune function.
• Immunoglobulin replacement therapy: This therapy involves taking immunoglobulin proteins, specifically IgG proteins, from donated blood plasma and injecting them intravenously into patients.
• Interferon therapy: Interferon is used to treat viral infections in people who are immunocompromised.