Loss of viral control tied to lymphoma risk

By David Douglas

NEW YORK (Reuters Health) - Patients who have abnormal reactive blood patterns when exposed to Epstein-Barr virus appear to have an increased risk of lymphoma, according to European researchers.

In the International Journal of Cancer, Dr. Silvia de Sanjose of the Catalan Institute of Oncology, Barcelona and colleagues note that although Epstein-Barr virus is often thought to be benign, infection with this virus may lead to processes that can disturb the regulation of the immune system and increase the risk of cell transformation to malignancies.

To investigate whether abnormal reactive patterns to Epstein-Barr virus might be related to the risk of malignancy, the team conducted an analysis of immune responses to Epstein-Barr virus-related proteins in 1,085 lymphoma patients and in 1,153 comparison (control) patients without lymphoma from five European countries.

Patients with active Epstein-Barr virus infection and abnormal activity of Epstein-Barr virus have a more diverse immune reaction pattern, yielding a broad reactive profile, the researchers explain.

Overall, 21 percent of the study subjects showed abnormal patterns. However, abnormal patterns were significantly greater in the lymphoma patients than in controls (23.9 percent versus 18.0 percent).

In addition, the team found that abnormal Epstein-Barr virus reactivity was a risk factor for all lymphomas, increasing the risk by 42 percent. The association was particularly strong for chronic lymphocytic leukemia, which was associated with a three-fold increased risk.

Women and the elderly appeared to have poorer control of Epstein-Barr virus replication.

The researchers point out that Epstein-Barr virus may be involved in the development of lymphomas in patients with a suppressed immune system more that previously thought, which is "probably explained by an underlying loss of immune control of Epstein-Barr virus latent infection."

In comments to Reuters Health, de Sanjose stressed that "these results could be used to monitor Epstein-Barr virus replication in particular circumstances," but at the moment can not be used to predict lymphoma in the general population.

SOURCE: International Journal of Cancer, October 2007.