This, in turn, might mean that these UVB-induced inflammatory cells contribute to the genesis of skin tumors and perhaps other tumors rather than simply facilitating cancer progression, as generally thought, Sullivan notes.
Normally, the body mobilizes the suppressor cells to limit immune responses to infection, sepsis or trauma so that healing can begin, Lesinski says.
"However, in the cancer setting, repeated UV light exposure or after other chronic or repeated inflammatory stimuli, these cells persist and become immunosuppressive," he says. "They can render helpful immune cells such as T cells or natural killer cells unable to recognize and eliminate cancer cells in the skin."
Lesinski, Oberyszyn, Sullivan and their colleagues conducted the study using a strain of hairless mice that develops squamous cell carcinoma of the skin the second most common skin cancer in humans when exposed to UVB.
The investigators also found that treating mice with topical catalase inhibited the migration of the suppressor cells into UVB-exposed skin, suggesting that the influx of these cells in males might be due to the relatively lower skin-catalase activity.
In fact, male mice with UVB-induced skin tumors had 55 percent more of the suppressor cells in the skin than did their female counterparts.
"This is the first report to our knowledge of a sex discrepancy in this group of inflammatory cells in tumor-bearing mice, and it suggests that our findings might translate to other types of cancer," says Oberyszyn, associate professor of pathology and a member of the OSUCCC James Molecular Biology and Cancer Genetics Program. "Men face a higher risk of numerous types of cancers, and relatively higher levels of inflammatory myeloid cells might contribute to this susceptibility."
|Contact: Darrell E. Ward|
Ohio State University Medical Center