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Immunity and infection prevention

Antigens and antibodies

The main article (“Antigens and antibodies”) explains what antigens and antibodies are. This topic looks at the practical side: why antibody levels fall in leukaemia, how they are measured and when immunoglobulin is given.

Last updated: ~1 min read
A ring with only a few Y-shaped antibodies.
Figure 1.Few antibodies: a thin safety net.

01Short answer

Antibodies are made by plasma cells, which come from B cells. In CLL and after some treatments (for example anti-CD20 antibodies, CAR-T and transplant), B cells fall and blood levels of IgG, IgA and IgM can drop; this is called hypogammaglobulinaemia. The result can be repeated chest, sinus and other bacterial infections. Your doctor measures immunoglobulin levels and, if needed, prescribes intravenous (IVIG) or subcutaneous immunoglobulin. Before a transplant, antibodies to viruses such as CMV and HLA antibodies are checked.

02Simple explanation

Few antibodies mean more bacterial infections.

IgG level is measured with a blood test.

Immunoglobulin is made from donor plasma and fills the gap.

03Scientific explanation

CLL: the disease itself disrupts normal B cells, so hypogammaglobulinaemia is common in CLL.

Serology: during treatment and after immunoglobulin infusions, antibody tests can mislead, because antibodies may come from donor plasma.

04What happens in the body?

When levels fall

The antibody “net” thins and bacteria, especially in the airways, multiply more easily.

Immunoglobulin infusion

Antibodies from the plasma of thousands of donors are usually given at regular intervals; the doctor reviews the benefit and need from time to time.

A bag of golden liquid.
Figure 2.An immunoglobulin infusion.

Before a transplant

Antibodies to CMV, hepatitis and other viruses, and HLA antibodies, are checked; this affects donor choice and prevention.

Tubes and a folder — Antigens and antibodies
Figure 3.Antibody tests before a transplant.

05The antibody-level pathway

Four steps.

Test — IgG is measured.1TestIgG is measured.
Gap — The level is low.2GapThe level is low.
Replacement — Immunoglobulin is given.3ReplacementImmunoglobulin is given.
Protection — Fewer infections.4ProtectionFewer infections.

06Antibody tests: what for?

TestPurpose
IgG, IgA, IgMOverall antibody reserve
Virus antibodies (serology)Past infection and risk
HLA antibodiesTransplant and platelet transfusions
Blood group antibodiesTransfusion compatibility

07Key terms

Immunoglobulin
The scientific name for antibody.
IgG
The most common antibody class in blood.
Hypogammaglobulinaemia
A shortage of antibodies.
IVIG
Intravenous immunoglobulin.
Serology
Testing for antibodies.

08Key points

  • CLL and some treatments lower antibodies.
  • Few antibodies raise bacterial infection risk.
  • IgG is measured with a blood test.
  • Your doctor prescribes immunoglobulin.
  • Antibodies are checked before a transplant.
  • Serology can mislead during treatment.

09Frequently asked questions

Is immunoglobulin always needed?

No; it is considered only when levels are low and there are serious or repeated infections.

What is the infusion like?

It usually takes a few hours; the first one is given more slowly and reactions are watched for.

If my antibodies are low, will vaccines work?

The response may be weaker; your doctor chooses the timing (“Vaccines”).

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. Is immunoglobulin always needed?

  2. What is the infusion like?

  3. If my antibodies are low, will vaccines work?

My questions

12Sources

  1. MedlinePlus (U.S. National Library of Medicine). Immune response
  2. InformedHealth.org (IQWiG) via NCBI Bookshelf. How does the immune system work?
  3. National Cancer Institute (NCI). Infection and Neutropenia during Cancer Treatment
  4. American Cancer Society. Infections in People with Cancer
  5. Blood, 2018. iwCLL guidelines for diagnosis, indications for treatment, response assessment, and supportive management of CLL
  6. World Health Organization (WHO). Hand hygiene
  7. World Health Organization (WHO). Five keys to safer food manual
  8. American Cancer Society. Signs and Symptoms of Acute Myeloid Leukemia (AML)
  9. American Cancer Society. Signs and Symptoms of Acute Lymphocytic Leukemia
  10. National Cancer Institute (NCI). NCI Dictionary of Cancer Terms: immunophenotyping
Medical disclaimerThis information is for educational purposes only and does not replace medical advice.
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