Blood cancers, including leukemia, lymphoma, and multiple myeloma, can profoundly affect the immune system in several ways, compromising its ability to defend against infections and maintain overall health. Here’s how blood cancer impacts the immune system:

1. Disruption of Normal Blood Cell Production

  • Bone Marrow Infiltration: Cancerous cells (leukemic blasts, lymphoma cells, myeloma cells) can infiltrate the bone marrow, crowding out healthy blood-forming cells (stem cells) responsible for producing red blood cells, white blood cells, and platelets.
  • Decreased Blood Cell Counts: This infiltration leads to a decrease in the production of mature blood cells, such as neutrophils (a type of white blood cell essential for fighting infections), red blood cells (critical for oxygen transport), and platelets (necessary for blood clotting).

2. Impact on White Blood Cells (Leukocytes)

  • Neutropenia: Many blood cancer treatments, particularly chemotherapy, can cause neutropenia—a severe reduction in neutrophil counts. Neutrophils are crucial for combating bacterial and fungal infections.
  • Lymphopenia: Reduction in lymphocyte counts, including T-cells and B-cells, which are vital components of the adaptive immune response. This can impair the body’s ability to recognize and fight infections effectively.

3. Increased Susceptibility to Infections

  • Immune Compromise: The combination of reduced blood cell production and chemotherapy-induced immune suppression increases the risk of infections, ranging from bacterial and fungal to viral infections.
  • Opportunistic Infections: Immunocompromised individuals are more susceptible to opportunistic infections, including those caused by pathogens that normally do not cause illness in healthy individuals (e.g., cytomegalovirus, Pneumocystis jirovecii).

4. Impact on Immune Surveillance

  • Immune Evasion: Some blood cancers can evade immune detection or manipulation, allowing them to proliferate unchecked and further suppress normal immune function.
  • Tumor Immune Microenvironment: Cancer cells may alter the local immune microenvironment, creating conditions that inhibit immune surveillance and promote tumor growth.

5. Treatment-related Effects

  • Chemotherapy and Immunotherapy: While these treatments target cancer cells, they can also suppress the bone marrow and immune system, leading to transient or prolonged periods of immune compromise.
  • Stem Cell Transplantation: Intensive treatments such as allogeneic stem cell transplantation involve conditioning regimens (chemotherapy and/or radiation) that can severely suppress the immune system, requiring careful monitoring and support to prevent infections.

6. Immune Reconstitution

  • Recovery Phase: After completing treatment, the immune system undergoes a period of recovery, known as immune reconstitution. This phase is critical as the body rebuilds its immune defenses and regains its ability to fight infections.

Management and Support

  • Prophylactic Treatments: Patients may receive prophylactic antibiotics, antiviral medications, or antifungals to prevent infections during periods of immune suppression.
  • Monitoring: Regular monitoring of blood counts and immune function helps healthcare providers assess infection risks and adjust treatments as needed.
  • Supportive Care: Adequate nutrition, hydration, and vaccination against preventable infections are essential components of supportive care to optimize immune function and overall health.


Blood cancers profoundly impact the immune system by disrupting normal blood cell production, compromising immune cell function, and increasing susceptibility to infections. Understanding these effects is crucial for managing treatment strategies effectively and supporting patients throughout their cancer journey. Advances in supportive care and treatment approaches continue to improve outcomes for patients with blood cancers, emphasizing the importance of comprehensive care that addresses both the cancer and its effects on immune health.

By Sue