Apoptosis and Bcl-2 expression in cultured murine splenic T cells

Immunology. 1995 Mar;84(3):375-82.


To elucidate the mechanism by which bcl-2 affects apoptosis in post-thymic T cells, we investigated the expression of Bcl-2 protein in primary cultures of splenic T cells and in the interleukin-2 (IL-2)-dependent T-cell line CTLL-2. The overall level of Bcl-2 was determined by immunoblotting, and the variability in Bcl-2 expression was determined by flow cytometry. For a few days after concanavalin A (Con A) plus IL-2 activation, the overall level of Bcl-2 in T cells remains unchanged, but it becomes more heterogeneous. By 5 days after activation, the expression returns to a more homogeneous distribution, but it is increased up to threefold above pre-activation levels, depending upon the dose of IL-2 supplied. When Con A blasts or CTLL-2 cells are deprived of IL-2 for 24 hr, there is no change in their overall Bcl-2 levels which remain homogeneous even though almost half of the cells are apoptotic. However, when bcl-2 transfected CTLL-2 cells are deprived of IL-2, they do not undergo apoptosis, and their endogenous Bcl-2 protein level slowly decreases relative to their total protein. These data document the IL-2-dependent expression of Bcl-2 in activated T cells, confirm the ability of deregulated bcl-2 to inhibit the onset of apoptosis after IL-2 withdrawal, but suggest that, after IL-2 withdrawal, a drop in Bcl-2 levels relative to total protein levels does not precede apoptosis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis / immunology*
  • Apoptosis / physiology
  • Cells, Cultured
  • Concanavalin A / immunology
  • Dose-Response Relationship, Immunologic
  • Flow Cytometry
  • Interleukin-2 / immunology
  • Lymphocyte Activation
  • Mice
  • Mice, Inbred C57BL
  • Proto-Oncogene Proteins / immunology*
  • Proto-Oncogene Proteins / metabolism
  • Proto-Oncogene Proteins c-bcl-2
  • Spleen / immunology*
  • Spleen / metabolism
  • T-Lymphocytes / immunology*
  • T-Lymphocytes / metabolism
  • Tumor Cells, Cultured


  • Interleukin-2
  • Proto-Oncogene Proteins
  • Proto-Oncogene Proteins c-bcl-2
  • Concanavalin A