Monoclonal gammapathies in long-term surviving rhesus monkeys after lethal irradiation and bone marrow transplantation.

Late effects of total body irradiation and subsequent autologous bone marrow transplantation on the development of age-related monoclonal gammapathies (MG) were studied in 14 long-term surviving Rhesus monkeys. Together with 27 untreated control monkeys, they have been followed up for more than 20 years. In contrast with the control group, the experimental monkeys developed MG with aging in higher frequencies, earlier and mainly of the benign MG category. One experimental monkey developed a multiple myeloma, the first observed in the nonhuman primates so far. These results indicate an accelerated senescence of the immune system in the experimental monkeys as a late consequence of tissue or cell damage during irradiation.