Suppressed Immune System

There are many different causes of immune suppression, including diseases, medications, and lifestyle factors. Autoimmune diseases are conditions in which the immune system produces self-targeting antibodies which cannot distinguish between self and non-self and mistakenly attack the body’s own cells. Treatment often requires the use of immunosuppressive drugs, including corticosteroids (the most common cause of drug-induced immune system suppression), antimetabolites (azathioprine, methotrexate), calcineurin inhibitors (tacrolimus, cyclosporin) and biological agents (rituximab, TNF-alpha inhibitors). Systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), and autoimmune hemolytic anemia are among the most common autoimmune conditions requiring the use of immunosuppressive medications. These medications are also used after organ transplantation to prevent the immune system from attacking the transplanted organ and causing rejection. Immunosuppression can also be a side effect of other treatments, such as some cytotoxic chemotherapy agents (i.e., drugs able to destroy cancer cells). In individuals undergoing chemotherapy, immunosuppression may occur during treatment and for a few months afterwards.  

Various viral and bacterial infections can also suppress the immune response. The most common cause of long-term viral immunosuppression is human immunodeficiency virus (HIV) infection, which can progress to acquired immune deficiency syndrome (AIDS). HIV infects and destroys CD4+ T cells, a major group of white blood cells involved in responding to viral pathogens. Therefore, the immune system is suppressed and vulnerable to other infections. Pneumonia is another cause of immunosuppression. Often the result of a bacterial infection (e.g., Staphylococcus aureus or Streptococcus pneumoniae), pneumonia causes inflammation and damage to the lungs, which in turn can suppress the immune system and increase the risk of future infections.  

Other diseases, including lymphoma, leukemia, and sickle cell disease, may affect the spleen, an important organ involved in the immune response, and also cause immune suppression. Lymphoma and leukemia are blood cancers that can cause a buildup of cancerous lymphocytes, red blood cells, and platelets in the spleen, resulting in spleen swelling (i.e., splenomegaly) and impaired function. In sickle cell disease, the characteristic sickle-shaped red blood cells can block the spleen’s blood vessels, also causing swelling and dysfunction. 

Rarely, immune system suppression may result from primary immunodeficiencies (i.e., a group of genetic disorders characterized by poor development or functioning of one or more immune cell types). These conditions typically affect one or more of the four main types of antibodies: IgA, IgE, IgG, and IgM. Each of which plays a specific role in fighting off pathogens. The most common types of primary immunodeficiencies include selective IgA deficiency (i.e., deficiency in the IgA antibody), X-linked agammaglobulinemia (i.e., deficiency in all classes of antibodies), and hyper-IgM syndrome (i.e., deficiency in IgA, IgE, and IgG antibodies).    

Occasionally, lifestyle factors, such as long-term alcohol misuse and severe malnutrition, may also result in a weakened immune system.  

Signs and symptoms of a suppressed immune system include frequent infections accompanied by severe constitutional symptoms, such as high fever, chills, and weakness.  An underlying immune response concern might be suspected in individuals requiring several courses of antibiotics per year. Specifically, the American Academy of Allergy, Asthma & Immunology suggests that if a child needs more than four antibiotic courses in a year, or an adult needs more than two, a healthcare professional should assess for underlying immune suppression. For both children and adults, having pneumonia twice in a lifetime, needing preventative antibiotics, or having chronic sinus infections may also indicate a suppressed immune system. 

Depending on the cause of the immunosuppression, additional symptoms may include fatigue, weakness, or body aches and pains.  

Individuals with a suppressed immune system are often monitored for the development of infectious diseases, and they can be educated on infection prevention measures, including guidelines for self-isolation and personal protective equipment (PPE). An individual may also practice lifestyle behaviors that support their immune system, such as getting adequate sleep, exercising regularly, and eating a balanced diet with lots of fruits and vegetables. If infection occurs, antibiotics, like amoxicillin, or antivirals, like oseltamivir, may be prescribed depending on the infectious agent. Additional treatment for a suppressed immune system depends on the underlying cause.  

HIV may be treated with antiretroviral therapy (ART), which aims to keep the virus from spreading throughout the body. HIV, as well as some cancers, may also benefit from immunomodulation therapy -  medications that improve and strengthen the immune response.  

Splenectomy (i.e., surgical spleen removal) may be considered in those with splenic dysfunction. Although an individual can survive without a spleen, this will increase their risk of infection and sepsis, especially from incapsulated bacteria. This is why vaccination against pneumococcus, meningococcus, and Haemophilus influenzae is advised after a splenectomy. 

For individuals with primary immunodeficiencies, the missing antibodies can be provided via intravenous immunoglobulin (IVG) therapy. Treatment can also include stem cell transplants or gene therapy, which promote the body’s intrinsic production of antibodies.  

When immunosuppression is caused by a medication, treatment usually focuses on relieving the unwanted side effects. Such treatment can include medications to treat nausea (e.g., ondansetron) and pain-relieving medications (e.g., aspirin, ibuprofen). If an infection occurs, the immunosuppressant’s dosage may be lowered, and depending on the infectious agent, antibiotics or antivirals may be prescribed. Less commonly, immunosuppressive medication may be discontinued.