White blood cells can help destroy cancerous tumors before they spread

TEL AVIV, Israel — A certain type of white blood cell may be the secret weapon doctors have been looking for in the fight against cancer. A new study finds eosinophils can help destroy cancerous tumors in the lungs and stop the disease from spreading.

Researchers from Tel Aviv University say these white blood cells produce destructive proteins which can kill cancer cells. They also have the power to summon the body’s natural cancer-fighting agents — the T-cells. The new findings about eosinophils may lead to the development of a new immunotherapy treatment for cancer patients.

Typically, eosinophils use their proteins to fight off parasites. However, in modern and extremely hygienic societies, these germ-fighters get much less work than in the past. As a result, eosinophils can actually end up causing problems like allergies and asthma when they overreact to certain substances entering the body.

Scientists turn eosinophils loose on cancer

white blood cells cancer
Proliferation metastatic tumor cells in animals with no eosinophils.
(CREDIT Tel Aviv University)

Professor Ariel Munitz and PhD student Sharon Grisaru suspected that they could take eosinophils and send them into battle against cancer cells instead of parasites.

“We chose to focus on lung metastases for two main reasons: First, metastases, and not the primary tumors, are often the main problem in treating cancer, and the lungs are a major target for the metastasis of many types of cancer. Second, in a preliminary study we demonstrated that eosinophils gather in tumors developing in mucous tissues like the lungs, and therefore assumed that they would be found in lung metastases as well,” Prof. Munitz explains in a media release.

The team started by examining human cancer tissues coming from the biopsies of breast cancer patients. The samples came from lung metastases after the cancer had spread to other organs. The study revealed that the white blood cells were able to reach the lung and then penetrate the cancerous tissue. From there, they released their destructive proteins, attacking the tumor.

Using animal models, researchers also discovered that eosinophils are able to stop cancer from metastasizing (spreading). Without eosinophils present, the lung metastases grew much larger than in lungs full of the white blood cells.

How do eosinophils do this?

“We observed that when eosinophils are missing, the tissue also lacks T-cells – white blood cells known for fighting cancer. Consequently, we assumed that eosinophils combat cancer through T-cells. Our next task was to understand the mechanism underlying this process,” Prof. Munitz reports.

Study authors made two important discoveries about these white blood cells. First, when the eosinophils detect cancer nearby, they release large amounts of chemokines — a substance that summons T-cells. Second, eosinophils release chemokines when the cells come into contact with two kinds of substances in the cancerous environment — IFN-g and TNF-a. Simply put, when IFN-g and TNF-a show up in a cancerous area of the body, eosinophils call for back-up and bring T-cells in to fight.

“Increasing the number and power of T-cells is one of the main targets of immunotherapy treatments administered to cancer patients today. In our study we discovered a new interaction that summons large quantities of T-cells to cancer tissues, and our findings may have therapeutic implications,” Prof. Munitz concludes.

“Ultimately, our study may serve as a basis for the development of improved immunotherapeutic medications that employ eosinophils to fight cancer in two ways: on the one hand, the eosinophils will attack the cancer directly by releasing their own destructive proteins, while on the other, they will increase the number of T-cells in the cancer’s environment. We believe that the combined effect can significantly enhance the effectiveness of the treatment.”

The study is published in the journal Cancer Research.