Difference in Uptake of Tritiated Thymidine by Myelocytes from Bone Marrow and Spleen in Chronic Myeloid Leukaemia

Aspirates obtained simultaneously from the bone marrow and the spleen in 19 patients with chronic myeloid leukaemia (CML) were incubated with tritiated thymidine (3HTDR). The labelling indices (LI) of the myelocytes were determined autoradiographically. With increasing leucocyte counts the LI of the bone marrow myelocytes did not change significantly. In the spleen aspirates there was a significant increase in the LI of the myelocytes with increasing WBC counts from 10, 000 to 300, 000. The results indicate that the granulopoietic tissue in the spleen is not functionally identical with that of the bone marrow in CML.