Chronic disorders of the immune system or the chronic administration of drugs to suppress the immune system (such as those used after an organ transplant) predispose a person to lymphoma. Exposure to radiation increases the risk too.
Several types of viruses have been linked. The Epstein-Barr virus, which causes infectious mononucleosis, is associated with African Burkitt's lymphoma. A T cell virus related to the HIV virus associated with AIDS has been linked to an aggressive T cell lymphoma found in Japan, the Caribbean and the southeastern United States.
The mechanism common to each of these appears to be a significant alteration in the normal regulation of the immune system.
