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Updated: Aug 10, 2026
Ex vivo Expansion of Tumor-reactive T Cells by Means of Bryostatin 1/Ionomycin and the Common Gamma Chain Cytokines Formulation
Published on: January 14, 2011
Protective role of IL-2 during activation of T cells with bryostatin 1
F J Kos1, D L Cornell, A B Lipke
1Department of Microbiology and Immunology, Virginia Commonwealth University, Richmond, VA 23298, USA. fkos@hsc.vcu.edu
Abstract:
Pharmacologic agents such as bryostatin 1 (bryostatin) can regulate cell activation, growth, and differentiation by modulating the activities of protein kinase C isoenzymes. Inhibition of growth of tumor cells and activation of T lymphocytes in vitro are the most recognized consequences of bryostatin treatment. The effect of bryostatin on T cells ranges from induction of apoptotic cell death to T cell activation, expansion, and acquisition of antigen-specific effector functions. Here, we describe the conditions under which these wide ranging effects occur. Mouse mammary tumor 4TO7-IL-2-primed lymph node cells exposed ex vivo to bryostatin upregulated CD25 expression but lost the ability to secrete IL-2. Most of these cells died by apoptosis unless IL-2 was provided for the duration of bryostatin treatment. Analysis of T cell repertoire by screening of T cells for the expression of different Vbeta T cell receptor (TCR) families revealed that bryostatin-induced T cell death was unbiased and Vbeta-nonspecific. Within particular Vbeta clones, only CD25(+) T cells survived exposure to bryostatin and IL-2. Treatment of 4TO7 tumor-bearing mice with a single injection of low dose bryostatin followed by multiple low doses of IL-2, but not with bryostatin alone, delayed tumor growth. These results indicate that activation of T cells with bryostatin should be carried out under protection of exogenous IL-2 to ensure survival and expansion of T cells that may exhibit anti-tumor activity.
Insights
Bryostatin can affect T cells, causing death or activation. Combining bryostatin with interleukin-2 (IL-2) promotes T cell survival and anti-tumor activity in mice.
Area of Science:
- Immunology
- Pharmacology
- Cancer Research
Background:
- Bryostatin 1 modulates protein kinase C, influencing cell processes like activation, growth, and differentiation.
- Bryostatin's effects on T cells are diverse, ranging from apoptosis induction to activation and effector function acquisition.
- Understanding the conditions governing these varied T cell responses is crucial for therapeutic applications.
Purpose of the Study:
- To define the conditions that dictate the diverse effects of bryostatin on T cells.
- To investigate the role of interleukin-2 (IL-2) in modulating bryostatin-induced T cell responses.
- To evaluate the therapeutic potential of combined bryostatin and IL-2 treatment in a murine tumor model.
Main Methods:
- Ex vivo culture of mouse mammary tumor 4TO7-IL-2-primed lymph node cells with bryostatin, with or without IL-2.
- Flow cytometry analysis of CD25 expression and IL-2 secretion.
- T cell receptor Vbeta repertoire screening to assess T cell death specificity.
- In vivo studies involving administration of bryostatin and IL-2 to 4TO7 tumor-bearing mice.
Main Results:
- Bryostatin treatment upregulated CD25 but inhibited IL-2 secretion in ex vivo T cells.
- Most bryostatin-treated T cells underwent apoptosis unless IL-2 was continuously supplied.
- Bryostatin-induced T cell death was Vbeta-nonspecific, with CD25(+) T cells surviving in the presence of IL-2.
- Combined low-dose bryostatin and IL-2 treatment delayed tumor growth in mice, unlike bryostatin alone.
Conclusions:
- Exogenous IL-2 is essential for the survival and expansion of T cells treated with bryostatin.
- Optimized conditions involving IL-2 protection enable T cell activation and potential anti-tumor activity.
- This strategy holds promise for enhancing T cell-mediated anti-tumor immunity in cancer therapy.
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