[Quantitative flow cytometric determination of cytoplasmic bcl-2 oncoprotein in peripheral blood lymphocyte subsets]

We measured serial changes of cytoplasmic bcl-2 oncoprotein in peripheral blood lymphocyte subsets after preparation of cell samples or cultivation with mitogen or interleukin-2 (IL-2) by two-color flow cytometry using monoclonal antibodies to lymphocyte subsets and human bcl-2. The bcl-2 levels determined by mean fluorescence intensity were diminished in most lymphocyte subsets when the samples were preserved at 4 degrees C for 6 hours or more without 1% paraformaldehyde (PFA) fixation. However, the bcl-2 levels were kept constant for a week or more in the samples preserved at 4 degrees C after immediate staining of cell surface markers and subsequent fixation with PFA. The percentages of CD4+ cells, CD8+, CD19+ cells and Fas+ cells became high when lymphocytes were cultured with concanavalin-A, and bcl-2 levels were also enhanced in these subsets. In addition, the bcl-2 levels were compared between lymphocytes cultured with and those without recombinant IL-2. IL-2 inhibited spontaneous decrease of bcl-2 in cultured lymphocytes. Apoptosis of the cultured lymphocytes was also determined by a flow cytometric method. IL-2 seemed to diminish apoptosis of cultured lymphocytes.