1. Virus infection of some animals have proved to be virus-induced lymphoma, that human lymphoma and proliferative diseases related to HIV infection.

     2. Immunodeficiency animal experiments proved that animals thymectomy lymphatic or anti-serum, the cells of poisons, radiation can be so long-term immune function in the lower state, the high incidence of tumors.

     3. Other factors lymphoma accompanied chromosomal abnormalities, such as Hodgkin’s disease commonly found three or tetraploid, Burkitt lymphoma and follicular lymphoma often T (14:18), and other chromosome changes. Drugs and the relationship between lymphoma have initially been confirmed.