Suppressive and antitumor activities of bone marrow cells and splenocytes of AKR mice during aging

In 4-month-old leukemia-prone AKR mice, the ability of bone marrow cells to inhibit proliferation of concanavalin A-stimulated splenocytes and mastocytoma P815 cellsin vitro was sharply increased in the preleukemic period. In 7-month-old mice, differences in natural suppressive activity of bone marrow cells were significant, but less pronounced than in 4-month-old mice. The immunosuppressive activity was not found in the spleen. In 4-month-old AKR mice, in the inhibition of proliferation of mitogen-stimulated splenocytes was increased due to enhanced NO production by bone marrow cells. These findings suggest that the increased antiproliferative activity observed in the bone marrow of AKR mice long before the appearance of clinical manifestations of leukemia is associated with disturbances in differentiation of myeloid progenitor cells and accumulation of natural suppressor cells in the bone marrow. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 127, No. 4, pp. 452–454, April, 1999