BCL1, a murine model of prolymphocytic leukemia. I. Effect of splenectomy on growth kinetics and organ distribution.

BCL1 is a transplantable murine B-cell leukemia that closely resembles human prolymphocytic leukemia (PLL). Syngeneic mice injected with BCL1 cells develop massively enlarged spleens followed by leukemia. Splenectomy performed either prior to BCL1 transplantation or prior to the leukemic phase of transplanted BCL1 results in a markedly altered clinical syndrome: the onset of leukemia is delayed by about 2 months; the leukemia is low-grade; and the lymph nodes, which are not prominently involved in leukemic animals with intact spleens, are massively infiltrated in the splenectomized transplant recipient. The immunologic phenotype of the BCL1 cell is not altered by splenectomy and thus does not appear to account for the altered tissue distribution of BCL1 in the splenectomized host. However, the results indicate a striking dependence of BCL1 on microenvironmental influences of the host lymphoid tissues.