The length of a biological marker is linked to respiratory infection in healthy adults.

Individuals were more likely to develop upper respiratory infection who were administered a cold virus and had shorter telomere lengths (a structure at the end of a chromosome) in specific cells than subjects with longer telomeres.

The finding came from a new study, led by Sheldon Cohen, Ph.D., of Carnegie Mellon University, Pittsburgh, and was published in JAMA.

Telomeres become shorter with each cell division, where they function as protective caps to stop erosion of genomic DNA.

When telomeres shorten in white blood cells, known as leukocytes, it suggests immunocompetece and is linked to poorer antibody reaction to vaccines.

The authors explained:

“Shorter leukocyte telomere length also is associated with aging-related illness and death from conditions with immune system involvement, including infectious diseases, cancer, and cardiovascular disease.”

However, scientists have not been able to determine whether the length of leukocyte telomeres is associated with acute disease in younger, healthy people.

Cohen and team set out to examine young to middle-aged adults to find out whether short telomeres in leukocytes, specifically CD8CD28- T cells, are linked to reduced resistance to upper respiratory infection and clinical disease.

The researchers evaluated the length of telomeres between 2008 and 2011 in peripheral blood mononuclear cells (PBMCs) and T-cell subsets (CD4, CD8CD28+ , CD8CD28-). A total of 152 healthy people between 18 and 55 years of age from Pittsburgh were involved in the study.

The subjects were each given their own room to stay in and were given nasal drops that consisted of rhinovirus 39 (a common cold virus). They were then observed for 5 days so that the experts could identify the development of infection and clinical illness.

Respiratory infections were found in 69% (n = 105) of the participants and 22% (n = 33) developed a clinical illness (common cold).

After exposure to RV39, shorter telomere lengths in all 4 kinds of cells were linked to greater chances of infection, according to the scientists.

The closest association with infection was found with CD8CD28- telomere length. Seventy-seven percent of people with the shortest telomeres in the CD8CD28- subset developed an infection, while 50% in the group with the longest telomeres developed one.

The experts found that only telomere length in the CD8CD28- subset was associated with a probability of clinical illness, with short telomere length linked to a greater risk.

Twenty-six percent of subjects with the shortest telomeres became clinically sick. Among the participants with the longest telomeres, 13% became ill.

Additionally, the significance of the link between CD8CD28- telomere length and infection elevated with increasing age. The researchers concluded:

“In this study of healthy young and midlife adults, shorter CD8CD28- cell telomere length was associated with upper respiratory tract infection and clinical illness following experimental exposure to rhinovirus. Because these data are preliminary, their clinical implications are unknown.”

Written by Sarah Glynn