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 splenectoized transplant recipient. The imunologic 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 indicates a striking dependence of BCL₁ on microenvironmental influence of the host lymphoid tissues.