Mouse red-cell rosettes in B-lymphoproliferative disorders

A high proportion of peripheral-blood lymphocytes formed spontaneous rosettes with mouse red cells in 22 out of 23 cases of chronic lymphocytic leukaemia (CLL); the proportion was significantly higher than in 19 cases of other B-lymphoproliferative disorders (non-CLL group) and in 19 normal controls. Intermediate findings were obtained in 10 cases of "hairy" cell leukaemia. Blast cells from various types of acute leukaemia did not bind mouse red cells. Pre-treatment of the lymphocytes with neuraminidase led to a significant increase in the proportion of rosettes in CLL only. This test may prove useful in distinguishing CLL from other B-lymphoproliferative disorders, particularly prolymphocytic leukaemia.