Rosette formation in acute lymphoid leukaemia.

The capacity of leukaemic lymphoblasts and remission lymphocytes, obtained from 40 children with acute lymphoid leukaemia, to form sheep red blood cell rosettes was investigated. Lymphoblasts isolated from the peripheral blood of the patients prior to antileukaemic treatment showed greatly reduced numbers of rosette-forming cells as compared to controls (4.6% vs. 27.5%). The ratio of rosette-forming cells during intensive induction chemotherapy was still significantly lower than the control value (15.7%), while after the achievement of complete remission the number of RFC approximated the normal value (22.5%). The presence of leukaemic serum had no significant effect on the number of RFC.