Null cell chronic lymphocytic leukaemia.

Lymphocytes lacking receptors for sheep erythrocytes and surface immunoglobulin were present in the blood in large numbers at some stage in four cases of chronic lymphocytic leukaemia (which included a mother and son), and formed a substantial proportion of the circulating lymphocytes in other cases. These null cells possessed receptors for mouse erythrocytes. Other B-cell markers were also found on these cells. Serial studies showed a great variation in the number of null cells during the course of the disease (which may be associated with treatment), suggesting variation in the the maturation of leukaemic cells, and indicating that the surface marker complement may not reflect the constitution of the cell undergoing the original malignant change.