Immunotherapy for Cancer with Designer T Cells

Uma Shankari By Uma Shankari, 11th Aug 2012 | Follow this author | RSS Feed | Short URL
Posted in Wikinut>Guides>Science>Biology>Biochemistry

Scientists have created a novel, hybrid immune cell that combines two kinds of immune cells—T cells and natural killer (NK) cells, which can destroy cancer cells.

Understang Our Immune System

Our body's immune system can distinguish what belongs to the body from everything foreign to it, and protect it against infections by foreign substances. It is also capable of fighting abnormal, dangerous cells and remove abnormal or dead cells.

The immune system’s primary defensive cells are the one trillion white blood cells or Lymphocytes, which are made in the bone marrow, the spongy inner part of the large bones. Lymphocytes are found in the blood, lymph nodes, and spleen.

There are three different types of lymphocytes: T cells, B cells, and natural killer (NK) cells. B cells grow to maturity independent of the thymus, and T cells are processed in the thymus, located in the upper part of the chest and mature there.

B cells secret soluble substances called antibodies into the body's fluids. Antibodies typically interact with circulating antigens such as bacteria and toxic molecules, but are unable to penetrate living cells. T cells, in contrast, interact directly with their targets, attacking body cells that have been infected by viruses.

About 5 to 16 percent of the total lymphocyte population contains natural killer cells. The term “natural” before killer cells means that natural killer cells don’t have to recognize a specific abnormality on a cell to be able to do their job. This is also called “innate immunity.” They are antigen nonspecific lymphocytes which recognize foreign cells of many different antigenic types.

Natural Killer Cells

Natural killer cells form the body's front line of defense. Unlike our other immune cells, natural killer cells are always alert and ready, while other disease-fighting cells take precious time—two to three days—to build forces and learn what the enemy looks like. When viruses and cancers attack, the cells keep the invaders at bay while the rest of the immune system prepares.

Natural killer are cytotoxic – that is, “cell killing.” Natural killer cells also produce substances known as cytokines, which assist the body in removing viruses and tumor cells.

Since natural killer cells are able to kill tumor cells, scientists are studying ways to increase the number or enhance the function of these cells in the body as a way to treat cancer more effectively.

How T Cells Function

T cells constantly patrol our bodies and scan for other cells that display ‘foreign’ peptides that indicate a cell is infected with a germ or has become cancerous. They recognize cells that don't belong in the body—such as bacteria—and activate other immune system players to sustain an attack on tumor cells.

The highly focused receptor is the T cell's strength but also its weakness. Because T cells are so specific, each patient's cancer would need different T cells to recognize its subtle variations, and there are just too few tumor-specific T cells in each patient.

Combining The Power of NK and T Cells

Scientists studied how T cells interact with the immune system microenvironment, recognize antigens and respond to cancer. They speculated if they could incorporate some of the traits of NK cells, the combination might be more effective against tumour cells.

The good thing about NK cells is that they don't target subtle differences in cells. They have a receptor called NKG2D on NK cells that recognize many types of cancer, such as lymphomas, ovarian, colon, myelomas, and melanomas.

Dr. Charles Sentman, an immunology researcher at Dartmouth Medical School and the Director of the Cancer Center's Immunology and Cancer Immunotherapy Research Program, has engineered a way to genetically alter T cells so that they are tumor specific and have an improved ability to seek out and destroy cancerous cells while leaving normal cells alone. This widens their "field of vision" so they can target many different tumors.

To make the new designer cells, Dr. Sentman removed T cells from patients with myeloma or ovarian cancer and reprogrammed them to include modified NKG2D receptors. These cells were able to efficiently kill the patient's own cancer cells.

The new immune cells attack the tumor directly and activate the immune system to be much more aggressive against the tumor.

Read Also

Understanding The Immune System


Antibodies, Antigens, Cancer, Cytotoxic, Immune System, Immunotherapy, Innate Immunity, Lymphocytes, Natural Killer Cell, Nk Cells, Nkg2D, T Cells

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author avatar Uma Shankari
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