Cell volume studies in B-cell leukaemia.

Leucocyte volume histograms were obtained in 12 cases of B-chronic lymphocytic leukaemia (B-CLL), two cases of B-prolymphocytic leukaemia (B-PLL) and two cases of hairy-cell leukaemia (HCL) by means of a Coulter model ZBl linked to a channelyser. Visual examination of the histograms showed differences between the cases which were confirmed by measurement of the modal volume (MV) and the sigma value (SD of log-volume). The MV of the cells in B-CLL ranged from 153.8 to 244.2 fl (mean 198.24 fl) and was lower than the MV in the cases of HCL (427.5 and 465.6 fl). One case of B-PLL had cells with an MV within the B-CLL range while in the other the MV was greater (317.9 fl). The histogram in one of two cases of B-CLL in 'prolymphocytoid' transformation showed a relatively high sigma value, thus suggesting heterogeneity in cell size. The volume histogram is a simple method of sizing the predominant cell in the peripheral blood in lympho-proliferative disorders and permits an objective comparison between cell sizes in different diseases.