Hairy cell leukemia: kinetics and intercellular relationships of cells in leukemic colonies grown in a semisolid...

We examined cellular relationships and cytokinetics of hairy cells in colonies formed in an in vitro cloning system. Cells in small colonies and at the periphery of larger ones were separated by wide, irregular intercellular spaces. Cells in the core of large colonies were elaborately intertwined by their cytoplasmic processes and so densely packed that their intercellularity was greatly reduced. Cell labeling with 3H-thymidine revealed indices ranging from less than 1% to 35%. The combination of autoradiography with a stain for tartrate-resistant acid phosphatase showed that the enzyme was not expressed by cells in S-phase. The cellular relationships of hairy cells in colonies grown in this system closely mimic those of their in vivo counterparts in the spleen and bone marrow.