Growth of pre-B cells in cultures of bone marrow from children with acute lymphoblastic leukaemia and other diseases.

Pre-B cells from the bone marrow of children with acute lymphoblastic leukaemia (ALL) survived up to 144 hr after the completion of treatment and divided in culture with maximum cell numbers at 24 hr. There was no rise in B cell number and no evidence of differentiation from pre-B to B cells. Binucleated pre-B cells in cultures containing cytochalasin B confirmed that pre-B cell division was occurring. Cycloheximide reduced cell numbers in culture but bromodeoxyuridine did not. Pre-B cell numbers also increased in culture of morphologically normal marrows from treated and untreated patients with solid tumours, and probably in normal marrows from patients with non-malignant diseases.