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Immunity and infection prevention

Immunosuppression

The main article (“How does the immune system work?”) explains immunity. This topic looks more deeply at the causes and types of immunosuppression, a state of weakened defence, and what it means in daily life.

Last updated: ~1 min read
A lowered dimmer and a fading shield.
Figure 1.Immunity is turned down like a dimmer.

01Short answer

Immunosuppression means the immune system works less well than normal. In leukaemia there are several causes: the disease itself (“How leukemia affects immunity”), chemotherapy, steroids, some targeted drugs and antibodies, radiotherapy and transplant. Sometimes immunosuppression is deliberate: after an allogeneic transplant, special medicines are given so that donor cells do not attack the body (graft-versus-host disease). The type matters: a lack of neutrophils mainly raises the risk of bacteria and fungi, a lack of T cells raises the risk of viruses and pneumocystis, and a lack of antibodies leads to frequent repeated bacterial infections.

02Simple explanation

Immunosuppression: weakened defence.

Causes: the disease, medicines, transplant.

Sometimes deliberate.

03Scientific explanation

Type and risk: neutropenia brings bacteria and fungi; T-cell deficiency brings viruses (such as herpes, CMV) and pneumocystis; antibody deficiency brings encapsulated bacteria.

Duration: steroids and some antibodies act for months after treatment, so prevention may continue.

04What happens in the body?

Like a dimmer

Immunity is not switched off but turned down, like a light; after treatment it slowly rises again.

Several causes

The disease, chemotherapy, steroids, antibodies and transplant can act together.

Five icons around a shield.
Figure 2.Several causes of immunosuppression.

Deliberate immunosuppression

After a transplant, medicines calm the donor cells and protect the body.

A cell cluster under a protective veil.
Figure 3.Medicines protect the graft.

05The course of immunosuppression

Four steps.

Start — Defence is normal.1StartDefence is normal.
Lowering — Treatment weakens defence.2LoweringTreatment weakens defence.
Careful period — Prevention and vigilance.3Careful periodPrevention and vigilance.
Recovery — Defence returns.4RecoveryDefence returns.

06Cause and main risk

CauseMain infection risk
Chemotherapy (neutropenia)Bacteria, fungi
SteroidsFungi, pneumocystis, viruses
Anti-CD20 antibodiesLow antibodies, viruses
Allogeneic transplantViruses (CMV), fungi, bacteria
CLLEncapsulated bacteria

07Key terms

Immunosuppression
Weakened immune defence.
Immunosuppressant
A medicine that deliberately weakens immunity.
Graft-versus-host disease
Donor cells attacking the body.
Opportunistic infection
A germ that causes illness only when immunity is weak.
Prophylaxis
Protective treatment in advance.

08Key points

  • Immunosuppression is weakened defence.
  • Several causes can act together.
  • The type determines the risk.
  • Sometimes it is deliberate and necessary.
  • The effect can last after treatment.
  • Do not stop medicines on your own.

09Frequently asked questions

I am immunosuppressed; what does that mean?

Your body is more vulnerable to infection; follow protection advice (“Preventing infection”).

How long does it last?

It depends on treatment: weeks to months, longer after a transplant (“Recovery of immunity”).

Why weaken immunity with medicines?

So that after a transplant the donor cells do not harm the body.

10Questions for your doctor

Take these questions to your appointment. The ones you save are collected on the “My questions” page and stay on this device only.

  1. I am immunosuppressed; what does that mean?

  2. How long does it last?

  3. Why weaken immunity with medicines?

My questions

12Sources

  1. National Cancer Institute (NCI). Infection and Neutropenia during Cancer Treatment
  2. MedlinePlus (U.S. National Library of Medicine). Immune System and Disorders
  3. American Cancer Society. Infections in People with Cancer
  4. U.S. Food and Drug Administration (FDA). Food Safety for Older Adults and People with Cancer, Diabetes, HIV/AIDS, Organ Transplants, and Autoimmune Diseases
  5. Journal of Clinical Oncology, 2008. Randomized Comparison of Cooked and Noncooked Diets in Patients Undergoing Remission Induction Therapy for Acute Myeloid Leukemia
  6. Memorial Sloan Kettering Cancer Center. Food Safety During Cancer Treatment
  7. Clinical Infectious Diseases (IDSA), 2014. 2013 IDSA Clinical Practice Guideline for Vaccination of the Immunocompromised Host
  8. Centers for Disease Control and Prevention (CDC). Altered Immunocompetence — General Best Practice Guidelines for Immunization
  9. MedlinePlus (U.S. National Library of Medicine). Immunization
  10. MedlinePlus (U.S. National Library of Medicine). Sepsis
Medical disclaimerThis information is for educational purposes only and does not replace medical advice.
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