Immunity: Get to Know Your Immune System!

Adequate sleep, proper nutrition, and regular exercise are 3 of the most important lifestyle factors that impact your health. Credit: Lansano (2021).

Autoimmune Diseases (Naturally- and Vaccine Induced) 

Although the immune system is responsible for defending the body against foreign pathogenic cells, the system may also mistakenly attack itself by targeting normal cells, thereby causing an autoimmune disease. There are around 80 autoimmune diseases of varying severity. Common autoimmune diseases include rheumatoid arthritis, lupus, coeliac disease, multiple sclerosis, type 1 diabetes, alopecia areata, and vasculitis.

According to Rosenblum et al. (2015), genetic susceptibility, environmental stimuli, and defective regulation are the main factors responsible for initiating autoimmunity. Genetic polymorphisms in immune-related genes such as HLA may result in a reduced threshold for autoreactive T-lymphocyte activation. T-cells are activated when enough T-cell receptors (TCR) are triggered by a presented antigen. Based on previous research conducted by Viola & Lanzavecchia (1996), the normal activation threshold is 8000 TCRs, but reduced thresholds require only 1500 TCRs for T-cells to respond to antigenic stimulation. On the other hand, environmental factors such as infection, the microbiome, or traumatic insult that create a pro-inflammatory environment initiates the activation of autoreactive T-lymphocytes. Regulatory T-cells (Tregs) are employed to suppress autoreactive T-cells to avoid unnecessary immune responses through the inhibition of T-cell proliferation (Kondelkova et al., 2010). However, defects in development, stability, or function may render Tregs dysfunctional, thereby unable to control autoreactive T-cell activity. Autoreactivity refers to immune responses against self-constituents such as healthy cells and issues, which then results in autoimmunity.

Initiation of autoreactivity caused by genetic predisposition, environmental triggers, and defective regulation. Credit: Rosenblum et al. (2015).

An example of an autoimmune disease caused by environmental stimuli is psoriatic arthritis. Psoriasis is a skin condition characterized by scales and itchy, dry patches. Environmental triggers for psoriasis include infections, cold, and psychological stress. An autoimmune reaction that affects the joints of psoriasis patients may then develop as a response to injury or high physical stress. For instance, a runner often experiences heel tendon damage as the muscle is constantly pulling on the bone to create movement. Repeated and long-term stress to the tendon exposes tissue that should not be in contact with blood cells. Once exposed, the immune system deploys blood cells to treat the exposure like a wound, but an abnormal immune response could cause inflammation of the joints and tendons (Orbai, 2022).

A topic of unending debate in medical literature is whether vaccines (e.g. influenza, hepatitis b, and human papilloma virus vaccine) may lead to allergies and autoimmune diseases (e.g. multiple sclerosis, rheumatoid arthritis, and vasculitis) via molecular mimicry— a significant similarity between certain vaccine-contained pathogenic elements and specific human proteins. Segal & Shoenfeld (2018) state that this similarity may result in immune cross-reactivity. Based on previous research, the human proteome shares up to 90% of viral pentapeptides and 99.7% of bacterial heptapeptides (Kanduc, 2010; Kanduc et al., 2008), indicating a high probability of immune cross-reactivity. 

However, Kanduc (2012) demonstrated that the immune system may perform tolerogenic mechanisms (Treg activation and proliferation as a second signal) to prevent autoimmunity. It was then suggested that an environmental factor— adjuvants— a variety of compounds added in a vaccine to stimulate immune response— impairs immune tolerance. Another counterargument, however, would be that immune responses to shared pathogenic elements is only possible due to the addition of adjuvants. Thus, the same genetic factor that causes autoimmunity— HLA DRB1— was suggested as another significant environmental trigger. In conclusion, exposure to shared pathogenic motifs and impaired immune tolerance as a result of genetic susceptibility and presence of adjuvants may result in autoimmunity after immunization.

The process leading to immune cross-reactivity and in genetically susceptible individuals after immunizations. Credit: Segal & Shoenfeld (2018).

Individuals are still advised to receive necessary vaccinations as vaccine-induced autoimmunity is extremely infrequent. Although autoimmune disorders cannot be cured, the condition can be controlled using various treatment methods according to physician advice. Anti-inflammatory drugs and corticosteroids can be prescribed to reduce inflammation and pain, while pain-killing medication such as paracetamol and codeine can help patients manage severe pain. Immunosuppressant drugs can also be digested to inhibit the responses of an overactive immune system, while deficiency treatments such as insulin injections to treat diabetes may be undergone. Other options include physical therapy to encourage mobility or surgery, for example to treat bowel blockage caused by Crohn’s disease.

Proper Behavioral Response to Vaccines 

In receiving vaccines, individuals are encouraged to maintain a cheerful, relaxed, and energetic mood. Based on a study done by Marsland et al. (2006), individuals with an overall happy and positive mood produced a 73% greater antibody response to hepatitis B vaccines as compared to those who reported feeling nervous, tense, or angry. According to Zaraska (2021), psychological and behavioral factors may significantly affect vaccine efficacy, specifically antibody production and inflammatory response. Optimism is known to switch immune-related genes away from an inflammatory response when preparing to defend the body from pathogens (Zaraska, 2021). Thus, individuals are highly recommended to get vaccinated with a positive state of mind. Cedars Sinai Hospital (2021) suggests  5 mood-lifting tips, namely to de-stress, sleep enough, connect socially, exercise, and cultivate gratitude to help boost your immunity after vaccinations. 

Happy moods during vaccinations help boost immunity. Credit: Cedars Sinai Hospital (2021).

Experience & Conclusion