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Interleukin-12 is a costimulatory cytokine for leukemic CD3+ large granular lymphocytes
1Department of Medicine, State University of New York at Syracuse 13210, USA.
Insights
Interleukin-12 (IL-12) acts as a costimulatory cytokine for the proliferation of leukemic large granular lymphocytes (LGL) when activated via the T cell receptor (TCR). This enhances understanding of LGL leukemia activation pathways.
Area of Science:
- Immunology
- Hematology
- Cell Biology
Background:
- Leukemic CD3+ large granular lymphocytes (LGL) proliferation mechanisms are not fully understood.
- Interleukin-12 (IL-12) is a cytokine with known immune-modulating functions.
- T cell receptor (TCR) signaling is a key pathway in T cell activation.
Purpose of the Study:
- To investigate the role of recombinant human interleukin-12 (rhIL-12) in the proliferation of leukemic CD3+ LGL.
- To determine if IL-12 acts as a costimulatory signal for LGL proliferation.
- To elucidate the interaction between TCR activation and IL-12 signaling in LGL leukemia.
Main Methods:
- In vitro proliferation assays using peripheral blood mononuclear cells (PBMC) and purified leukemic LGL from CD3+ LGL leukemia patients.
- Stimulation with anti-CD3 monoclonal antibody (MoAb) and/or rhIL-12.
- [3H]thymidine incorporation assay to measure proliferation.
- Radiolabeled IL-12 binding studies to assess IL-12 receptor expression.
- Neutralizing antibody experiments to block IL-12 activity.
Main Results:
- Anti-CD3 MoAb significantly stimulated PBMC proliferation in LGL leukemia patients.
- rhIL-12 alone had a minimal effect on proliferation.
- The combination of anti-CD3 MoAb and rhIL-12 resulted in a synergistic proliferative response.
- Purified leukemic LGL showed similar proliferation patterns, indicating direct stimulation.
- Anti-CD3 MoAb upregulated IL-12 receptors on LGL.
- Neutralizing IL-12 partially inhibited the anti-CD3 MoAb-induced proliferation.
Conclusions:
- IL-12 acts as a costimulatory cytokine for the proliferation of leukemic LGL activated through the TCR.
- IL-12 plays a significant role in the activation pathway of leukemic LGL via TCR stimulation.
- These findings contribute to understanding the pathogenesis of LGL leukemia and potential therapeutic targets.
Abstract:
The activation signals leading to proliferation of leukemic CD3+ large granular lymphocytes (LGL) are incompletely understood. In this study, the role of recombinant human interleukin-12 (rhIL-12) alone or in combination with other activation signals was studied in vitro. Anti-CD3 monoclonal antibody (MoAb) alone caused marked stimulation of peripheral blood mononuclear cells (PBMC) from three CD3+ LGL leukemic patients, whereas rhIL-12 alone had less effect as measured in a [3H]thymidine incorporation assay. The combination signals of anti-CD3 MoAb and rhIL-12 produced a proliferative response greater than anti-CD3 MoAb alone or rhIL-12 alone. Leukemic LGL, purified by CD8+ affinity chromatography, showed similar proliferative responses as PBMC from LGL leukemic patients, suggesting that the observed effect was indeed due to direct stimulation of leukemic LGL. Radiolabeled IL-12 binding studies demonstrated that anti-CD3 MoAb upregulated the number of IL-12 receptors per cell on PBMC from these patients. Neutralizing antibody to rhIL-12 partially blocked the proliferative response to anti-CD3 MoAb suggesting involvement of IL-12 in the pathway of activation of leukemic LGL via stimulation of the T cell receptor (TCR) (mimicking activation by antigen). These results show that IL-12 acts as a costimulatory cytokine for proliferation of leukemic LGL activated through the TCR in vitro.