The UA Department of Immunobiology and the UA’s Arizona Center on Aging were awarded an $11.8 million grant from the National Institutes of Health to study the decline of immunity in the elderly.

“”The overall purpose of the study is really to understand why immunity in old people declines so drastically,”” said Dr. Janko Nikolich-Zugich, head of the immunobiology department. “”We’re working to fix it.””

Nikolich-Zugich, the primary investigator of the study, said infections are one of the top five causes of death in people over the age of 65.

“”We don’t like that statistic, so that’s something we’re trying to change,”” said Kristin Renkema, a third-year immunobiology graduate student working on the study.

Previous research has shown parts of the immune system decline with age, and the most dramatic decline happens with T-lymphocyte cells, also known as T-cells. They are part of the adaptive immune system and they attack viruses with high precision, Nikolich-Zugich said.

The problem that elderly people are facing is that the number of T-cells in their bodies decrease with time, he said.

“”We have also discovered that those (T-cells) that are around do not get activated the way that they should be and they cannot divide as robustly as they did in youth,”” he said.

In the course of an immune response, it is very important for cells to multiply, Nikolich-Zugich said. Normally, expansion and division of cells takes place, but the frequency of that process declines in older people. The division of cells and the process of differentiation are impaired, he said.

In past work, researchers have identified some of these defects in a model using mice. They are now trying to apply it to human treatment and new vaccines that might allow older organisms to better defend the body against infection.

Renkema works primarily with the mouse model. Her project examines the aging defects in the T-cell itself, she said.

“”We have actually found some defects in the components of the cell that seem to be a common defect that can cause the broad-scale defects we see in the immune system,”” Renkema said.

The thymus gland, which is how the T-cell received its name, greatly reduces manufacturing cells at the time of puberty, Nikolich-Zugich said. It shrinks and produces less than one-tenth of what it produced before. The cells that have been around for a considerable amount of time do not respond well when infections hit.

The two major parts of the immune system are the innate immune system and the adaptive immune system, Nikolich-Zugich said. The innate system works to detect the infection and to contain it in order to slow it down, it also alerts the adaptive system. The adaptive immune system works to adjust to the specific bug that someone is infected with, he said.

“”Once the adaptive immune system gets up and gets activated, it will produce this whole army of cells that are going to go and fight the infection,”” Nikolich-Zugich said, “”and those cells are going to be different types of cells.””

Some cells will make the chemicals that kill the bacteria or stop and slow down the virus, and some will make antibodies that will bind to the virus and neutralize it to whisk it away, he said.

The system to fight infections is highly coordinated. Understanding exactly which parts of the immune system are declining and aging is the first and most important step in putting an end to more serious infections for older adults, Nikolich-Zugich said.

One level of intervention would be to give elderly people a very specialized type of vaccine. A vaccine that would be tailored to what the old immune system was and one that would make T-cells stronger and be activated more quickly, he said.