Immune System & CLL

Chronic lymphocytic leukemia (CLL) affects how the immune system works. The leukemia cells are abnormal B lymphocytes that do not function properly, which makes it harder for the body to fight infections.

As CLL develops, levels of protective antibodies may decrease. This can increase the risk of infections, particularly sinus infections, pneumonia, and skin infections.

How CLL Affects Immunity

Although CLL begins in B cells, it also impacts other parts of the immune system—especially T cells, which play a critical role in coordinating immune responses.

In CLL:

• T cells may not function normally
• The body may have difficulty responding to viruses
• Certain viruses, such as herpes zoster (shingles), can reactivate
• Responses to vaccines may be less effective

These changes make it more difficult for the immune system to recognize and respond to infections.

Effects of Treatment

Treatment for CLL can further affect immune function. While therapies are effective at reducing leukemia cells, they may also temporarily lower normal immune cells, increasing infection risk for several months.

Even after successful treatment, some underlying immune system changes may persist.

Autoimmune Complications

CLL can also disrupt normal immune regulation, leading the body to mistakenly attack its own cells. This may result in autoimmune conditions, most commonly:

• Autoimmune hemolytic anemia (destruction of red blood cells)
• Immune thrombocytopenia (low platelet counts)

These complications can contribute to symptoms and may require additional management.

Ongoing Research

Researchers continue to study how CLL affects the immune system and how these changes can be reversed. New approaches aim to:

• Restore normal immune function
• Reduce infection risk
• Harness the immune system to better target and eliminate CLL cells

Advances in this area are helping improve both outcomes and quality of life for patients living with CLL.