Leukocyte membrane proteins in chronic lymphocytic leukemia, as studied by two-dimensional gel electrophoresis

We evaluated protein expression in leukocytes from 20 patients with chronic lymphocytic leukemia (CLL), including one with the rare T-cell form of the disease. To identify proteins that potentially could be used to characterize leukemia or as candidates for new markers of differentiation, we studied cell and membrane extracts from these leukemic cells. We used immune precipitation and extraction of integral membrane proteins with Triton X-114 to identify known proteins on the surface of these cells. Extraction with Triton X-114 in the presence of protease inhibitors yielded reproducible membrane extracts, which we examined by two-dimensional gel electrophoresis. Of the approximately 2000 proteins or protein subunits so resolved from cell lysates and the 450 from membrane extracts of leukocytes from patients with T- and B-cell CLL, we were able to identify spots corresponding to the proteins designated by the OKT.4 and OKT.10 antibodies, the human class I and II histocompatibility antigens, beta 2-microglobulin, and surface IgM. We also defined sets of proteins that are characteristically expressed on the membranes of leukemic T or B cells, some of which correspond to previously defined markers of normal leukocyte subpopulations.