How does the immune system work when you have cancer?
Every second of every minute of every day, a battle between good and evil unfolds inside your body. The good news is the immune system, armies of cells designed to protect the body from disease and infection. Evil comes in the form of pathogens, viruses, bacteria, and mutated cells programmed to cause harm. When it comes to Cancer, the good guys don’t always win. But new immunotherapies, emerging technologies, and ongoing research are giving clinicians more tools to help the immune system do the job it was meant to do: fight threats like cancer. More developments are happening online as cancer researchers learn more about how the immune system works, how cancer hides from immune cells, and how certain immune cells actually help cancer grow. What they discovered is that the immune system is a complex system that protects the body, and in some cases helps cancer destroy it.
“The immune system is critical in fighting cancer,” says Stephen Lynch, MD, a receptionist and primary care physician at our hospital near Phoenix. “We have an immune system designed to recognize the original and non-native cells that can harm us. The problem is that it doesn’t always work. Other times, it works against us.”
The immune system is an efficient and powerful biological machine. Certainly from millions of germs and fights viruses and infections. Their responses are so powerful that they can cause fever, aches and pains, inflammation, and swelling. “It’s because your immune system has improved, it’s doing what it’s supposed to do,” says Dr. Lynch. And what it does is more than fight disease. Researchers at Northwestern University conclude that immune cells known as macrophages stimulate heart muscle cells, which helps keep the heart beating and maintains a steady beat. Swedish researchers have also found evidence that immune cells kill dead brain cells after a stroke and release substances that can allow the brain to repair damage. However, at the same time, scientists are learning how cancer cells not only evade the immune system’s defenses, but actually use immune cells to facilitate their attack on the body.
In military terms, the immune system consists of two parts: innate and acquired. Within each department are different cell systems that perform specific immune functions. Innate immunity is the body’s first line of defense. These immune cells are programmed to attack cells they perceive as a threat to the host. “Innate immune cells are killed first and questions are asked later,” joked Dr. Jeffrey Weber, deputy director of the Perlmutter Cancer Center in New York City. Cells of the innate immune system include:
Macrophages: Named for the Greek words meaning “big eaters,” these long-ended cells are true to their nickname. They are voracious, and use flexible tendrils to attach and attack their targets.
Neutrophils: These short-lived cells are the first line of defense against infection. They kill the bacteria and then die, forming pus.
Stem cells: These are the innate traffic cops of the immune system, directing T cells and B cells toward their targets.
Mast cells and basophils: They produce histamines that help the immune system attack allergens.
Natural killer (NK) cells: These fast-responding cells attack viruses and can be aggressive in attacking precancerous cells and cancer cells.
The acquired immune system, also called adaptive immunity, is more developed and takes longer to develop a plan of attack. Adaptive immune cells are:
B cells: They develop and mature in the bone marrow and produce proteins called antibodies that fight viruses and bacteria.
T cells: They also form in the bone marrow but mature in the thymus. There are two main types of T cells: helper T cells that stimulate B cells to produce antibodies, and killer T cells that attack the cells directly.
Adaptive immune cells target viruses or bacteria, using information provided by dendritic cells and other fungal cells, and store information about these pathogens so they can identify and attack them again if they launch another attack.
But if the immune system is so strong and developed, why does it often fail in the fight against cancer? The short answer: Because cancer is controlling it. “I tell my patients that if we don’t have an immune system, we’ll all get cancer,” says Alan Tan, MD, medical director of hematology and immunotherapy and an oncologist and hematologist at our hospital near Phoenix. “There is a delicate balance between the burden of a cellular mutation and how well the immune system can fight it. It is always on the alert for threats. And when the immune system overwhelms a tumor it fails to recognize and respond to the tumor. The threat.”
In fact, it’s possible, and even likely, that your immune system could be able to fight off cancer or precancerous conditions on a regular basis without your knowledge. “We all have a mechanism to filter out a small number of cancer cells to prevent us from developing visible cancer in the body,” says Dr. Tan. “Over time, that balance is lost.”
The tipping point at which cancer begins to overwhelm the immune system is not always known. “There are many different causes that can happen,” says Dr. Lynch. “Something to do with the DNA of the tumor. Something to do with the strength of the cancer.” But research has shown that cancer cells have a tremendous effect on certain innate and adaptive immune cells and recruit them to help cancer grow and travel. Researchers from the Augusta University Georgia Cancer Center report that they have found evidence that cancer cells use immature immune cells called bone marrow-derived suppressor cells (MDSC) to proliferate. Using misleading signals, cancer cells inhibit the growth of MDSCs and use them to aid in the spread of tumors. “These cells are essential to the successful spread of cancer,” said Dr. Hasan Kurkaya of the Georgia Cancer Center. Everyday science .“There is a very complex balance in the immune system that is generally anti-tumour, which means that it kills tumors, but in some cases, if this balance is disturbed, these cells can help tumors grow and become metastatic disease.”
stimulating the immune system
An article in Nature describes how tumour-associated macrophages (TAMs) aid in the formation of breast tumors. Macrophages are often found in large numbers in some breast tumors. While they are able to attack cancer cells, “macrophages within breast tumors have an unintended license to promote tumor growth and metastasis.” The nature of the temperament of the article says. Researchers and students at Albert Einstein College of Medicine report that they captured the process on video. The movie shows macrophages and breast cancer cells in mice working in tandem to help cancer cells enter the bloodstream.
Research suggests that an immunotherapy drug that targets TAMs and other innate cells can stimulate the immune system to attack tumors. Doctors at the Dana-Farber Cancer Institute are screening a compound called TMP195 designed to reactivate TAMs to attack cancer cells. Research has shown that this process reduces breast cancer tumors in mice. In 2015, the FDA approved elotuzumab (Empliciti ™ ), considered an immunostimulant drug, to treat multiple myeloma. “Not only does this drug target multiple myeloma cells, it also enhances natural killer cells,” says Dr. Tan. “Myeloma cells can suppress natural killer cells. But as myeloma cell population decreases, so does the number and function of natural killer cells.”
As researchers continue to study immunotherapy drugs that recharge innate immune cells, significant progress has been made in developing drugs that activate T cells, a key component of the adaptive immune system. In August, the U.S. Food and Drug Administration approved the first adoptive cell transfer therapy that uses modified immune cells called chimeric antigen receptor (CAR) T cells. These cells use the patient’s own T cells that are modified with a gene, produced in the laboratory by billions, and then injected back into the patient to attack specific cancer cells. The treatment has been approved for young patients with acute lymphocytic leukemia, and ongoing research is exploring whether it can be used to treat other liquid cancers.
Unlike chemotherapy and radiotherapy, which kill cancer cells directly, immunotherapy drugs do not attack cancer cells, but rather activate the body’s powerful immune system. “The immune system is very important in fighting cancer,” says Dr. Lynch. “Immunotherapy isn’t about getting there and killing the cancer cells. It just removes the mask of the cancer cell it’s trying to hide and allows the immune system to recognize it and do the job it was designed for.”
Learn more about immunotherapy.