December 17, 2007
Immune Naive T Cell Aging Cuts Their Numbers

Because immune cells circulate in the blood they strike me as great early candidates for development of rejuvenating stem cell therapies. The cells in the blood are more accessible and replaceable than cells which living in complexly shaped organs. A great target for youthful cell development are the naive T cells which age and become less able to divide.

PORTLAND, Ore. – Researchers at Oregon Health & Science University have uncovered new information about the body’s immune system in a study that suggests new strategies may be in order for protecting the country’s aging population against disease. The research is published in the current edition of the Proceedings of the National Academy of Science.

The research focused on an important component of the body’s immune system, a certain type of white blood cell called naïve T-cells. These cells are called naive because they have no experience of encountering germs. However, once they encounter germs, they learn and adapt to become strong defenders of the organism. The cells play an important role in the vaccination process because vaccines, which contain either weakened or dead viruses, teach naïve T-cells how to recognize germs and prepare the body for fighting infectious diseases at a later date. Previous research shows that an individual’s supply of naïve T-cells diminishes over their lifetime, meaning that in old age a person is more susceptible to infections such as the flu.

“Our research identified one actual process by which naïve T-cells are lost later in life,” explained Janko Nikolich-Zugich, Ph.D., a senior scientist at the OHSU Vaccine and Gene Therapy Institute and the Oregon National Primate Research Center and a professor of molecular microbiology and immunology in the OHSU School of Medicine.

“Throughout our lives, naïve T-cells divide very slowly in our bodies. This helps maintain sufficient numbers of naïve T-cells while we are young. As we age, naïve T-cells are lost and the remaining ones speed up their division to make up for the losses in their numbers. Interestingly, after a certain point, this actually causes the numbers of naïve T-cells to dwindle over time. Our data shows that once the number of naïve T-cells drops below a critical point, the rapidly dividing naïve cells are very short lived. Based on this finding and other information, research suggests that some of the aging Americans may be better protected against disease by finding a way to jumpstart production of new naïve T-cells instead of through revaccination.”

Infectious disease kill a lot of elderly people because their immune systems become too weak to hold off infections. But that is not the only way that immune system aging costs us. Aged immune systems are less able to fight off cancer and immune system aging might even be the biggest cause of the increasing incidence of cancer seen as people age.

We need to find a way to create youthful naive T cells to inject into us. Such cells would at least partially rejuvenate our immune systems and by doing so reduce our risk of cancer and infectious diseases.

Share |      Randall Parker, 2007 December 17 10:27 PM  Aging Mechanisms

Fly said at December 18, 2007 6:23 PM:

Each day about 100 hematopoietic stem cells circulate around in the blood and then take up residence in the empty bone marrow niches again. Merely by injecting a few hundred enhanced stem cells each day, the existing reservoir of bone marrow stem cells could be replaced. No radiation would be needed to kill the original stem cell population.

I expect some company to develop a hematopoietic stem cell culture to produce unlimited quantities of cells compatible with all humans and optimized for cardiovascular and immune system health. For little cost and with an injection each day for a few weeks, several body systems might be rejuvenated.

Fly said at December 20, 2007 10:25 AM:

"The stem cell lines are “HLA-homozygous,” meaning that they have a simple genetic profile in the critical areas of the DNA that code for immune rejection. The lines could serve to create a stem cell bank as a renewable source of transplantable cells for use in cell therapy to replace damaged tissues or to treat genetic and degenerative diseases."

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