Immune cells and Cancers

How Immune Cells Fight Cancer

• Recognizing Cancer Cells:

Cancer cells arise from normal cells through mutations, and they display unique molecular markers (antigens) on their surface.

Immune cells can recognize these antigens, identifying the cancer cells as enemies.

• Killing Cancer Cells:

Once cancer cells are identified, immune cells launch an attack. Examples include:

Cytotoxic T cells: These cells directly kill cancer cells.

NK cells (Natural Killer cells): These cells recognize and kill abnormal cells, including cancer cells.

Macrophages: These cells engulf and digest cancer cells.

• Remembering Cancer Cells:

Immune cells have memory. They can remember the antigens of cancer cells, allowing them to mount a rapid and effective attack if the same cancer cells reappear.

Why Do Immune Cells Sometimes "Fail" in Their Duty?

Although immune cells are very powerful, cancer cells are also very cunning. They evade the immune system's attacks in various ways, causing immune cells to "fail" in their duty. Here are some common escape mechanisms:

•  Camouflaging Themselves:
  

 Cancer cells can alter their surface antigens, disguising themselves as normal cells to evade recognition by immune cells. For example:

Downregulation of MHC molecules: MHC molecules are like the "identification cards" on cell surfaces. Cancer cells can downregulate MHC molecules to evade recognition by immune cells.

Expression of immune checkpoint molecules: Cancer cells can express immune checkpoint molecules like PD-L1, inhibiting the activity of T cells.

• Suppressing Immune Cells:
  

Cancer cells can release inhibitory molecules to suppress the function of immune cells. For example:

TGF-β: Inhibits the activity of T cells and NK cells.

IL-10: Inhibits the function of macrophages and dendritic cells.

Creating an Immunosuppressive Environment:

Cancer cells can alter their surrounding environment to create an immunosuppressive environment. For example:

Recruiting regulatory T cells: Regulatory T cells (Tregs) can suppress the function of other immune cells.

Secreting metabolic byproducts: Cancer cells can secrete metabolic byproducts like lactic acid, inhibiting the function of immune cells.

• Evading Immune Memory:

Cancer cells can continuously mutate, changing their surface antigens and evading the memory of immune cells. This is one of the reasons why cancer is prone to relapse and metastasis.

How to Help Immune Cells "Fulfill Their Duties"?

• Immune Checkpoint Inhibitors:

Immune checkpoint inhibitors are a novel type of cancer treatment that blocks the suppression of immune cells by cancer cells, restoring immune cell activity. Examples include:

PD-1/PD-L1 inhibitors: Block the binding of PD-1 and PD-L1, restoring T cell activity.

CTLA-4 inhibitors: Block the inhibitory signals of CTLA-4, enhancing T cell activity.

• CAR-T Cell Therapy:

CAR-T cell therapy is a personalized cancer treatment that modifies a patient's T cells to recognize and kill cancer cells. CAR-T cell therapy has achieved remarkable results in treating certain hematologic malignancies (such as leukemia and lymphoma).

• Cancer Vaccines:

Cancer vaccines are a method for preventing or treating cancer by activating the immune system to enhance attacks on cancer cells. Examples include:

HPV vaccine: Prevents cervical cancer.

Personalized cancer vaccines: Designed based on a patient's tumor antigens.

• Combination Therapy:

Combination therapy is a comprehensive cancer treatment approach that enhances attacks on cancer cells by combining multiple treatment modalities (such as chemotherapy, radiation therapy, and immunotherapy). Combination therapy can improve treatment outcomes and reduce recurrence and metastasis.