Analysis and isolation of leukaemic and residual normal B lymphocyte populations from patients with chronic lymphocytic leukaemia.

Two colour fluorescent staining using anti-Leu-1 and anti-B1 monoclonal antibodies has been combined with continuous flow microfluorimetry to analyse and isolate the T and B cell populations in B cell chronic lymphocytic leukaemia (B-CLL) patients. In Rai stage 0 patients two distinct B1 positive populations were detected and sorted; one was Leu-1- and the other Leu-1+. Analysis of the isolated populations showed that the former (Leu-1- B1+) represented the residual normal B cells, whereas the latter represented monoclonal CLL B cells. Short term culture of these cells in vitro showed that the Leu-1+ B1+ population secreted IgM, but not IgG, following PMA stimulation.