Presence of prelymphoma cells in the bone marrow of the lymphomagenic virus-treated AKR mouse.

Prelymphoma cells (PLC) are defined as cells which give rise to lymphoma cells but are not in themselves autonomous. They are present in the bone marrow of young AKR mice, a strain with a high natural incidence of thymic lymphoma. PLC are identified by transfer of AKR bone marrow into 400-rad-treated F1 recipients, one of the parents being AKR. Normal 1-month-old AKR bone marrow cells result in thymic lymphomas of AKR type in the hybrid recipients after latent periods of 6 to 16 months. In the present study, PLC resulting in lymphoma of AKR type 3 to 4 months after inoculation to irradiated hybrids are described. They are consistently found in the bone marrow of 21- to 28-day-old AKR mice treated at 3 to 5 days of age with a lymphomagenic virus, SL3-3. Long-term culture of these bone marrow cells allows the survival of totipotent hemopoietic stem cells but not of PLC. Thymic stromal remnants prepared from the 21- to 28-day-old virus-treated mice efficiently replicate oncogenic virus; however, they do not contain PLC. This was determined by grafting the remnants to irradiated and nonirradiated hybrid recipients. No AKR type lymphomas developed in the grafted mice. We conclude that the bone marrow of young oncogenic virus-treated AKR mice contains PLC modified by oncogenic virus so that they can produce thymic lymphomas after a shorter latent period than can PLC found in 1-month-old normal AKR mice. The modified PLC are not derived from totipotent marrow stem cells or sequestered in the thymic stroma of virus-treated mice.