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Updated: Nov 2, 2025
Tailoring In Vivo Cytotoxicity Assays to Study Immunodominance in Tumor-specific CD8+ T Cell Responses
Published on: May 6, 2019
T cells, particularly activated CD4+ cells, maintain anti-CD20-mediated NK cell viability and antibody dependent
Zhaoming Wang1, Michael S Chimenti2, Christopher Strouse3
1Cancer Biology Graduate Program, Holden Comprehensive Cancer Center, Carver College of Medicine, The University of Iowa, Iowa City, IA, USA.
Abstract:
Anti-CD20 monoclonal antibody (mAb) therapy is a mainstay of therapy for B cell malignancies, however many patients fail to respond or eventually develop resistance. The current understanding of mechanisms responsible for this resistance is limited. When peripheral blood mononuclear cells of healthy donors were cultured with Raji cells for 7 days, rituximab (RTX) induced NK cell-mediated antibody-dependent cellular cytotoxicity (ADCC), enhanced NK cell viability and increased or maintained NK expression of CD56, CD16, CD57 and KIR. T cells, mainly CD4+, mediated these changes in a contact-dependent manner, with local T cell production of IL2 playing a central role. Similar findings were found when autologous B cells were used as target cells demonstrating the need for T cell help was not due to allogenic reaction. Results with other anti-CD20 and anti-EGFR antibodies were consistent. Small numbers of T cells activated by anti-CD3/CD28 beads or bispecific antibody enhanced RTX-mediated NK cell ADCC, viability and phenotypical changes. Pathway analysis of bulk NK cell mRNA sequencing after activation by RTX with and without T cells was consistent with T cells maintaining the viability of the activated NK cells. These findings suggest T cell help, mediated in large part by local production of IL2, contributes to NK cell ADCC and viability, and that activating T cells in the tumor microenvironment, such as through the use of anti-CD3 based bispecific antibodies, could enhance the efficacy of anti-CD20 and other mAb therapies where NK-mediated ADCC is a primary mechanism of action.
Insights
T cells enhance anti-CD20 monoclonal antibody (mAb) therapy by boosting NK cell-mediated antibody-dependent cellular cytotoxicity (ADCC) and viability, largely through IL2 production. Activating T cells may improve mAb efficacy in B cell malignancies.
Area of Science:
- Immunology
- Oncology
- Pharmacology
Background:
- Anti-CD20 monoclonal antibody (mAb) therapy is crucial for B cell malignancies but faces challenges with patient response and resistance.
- Mechanisms underlying resistance to anti-CD20 mAb therapy are not fully understood.
- Natural Killer (NK) cells are key mediators of antibody-dependent cellular cytotoxicity (ADCC) in mAb therapy.
Purpose of the Study:
- To investigate the role of T cells in mediating the efficacy of anti-CD20 mAb therapy.
- To elucidate the mechanisms by which T cells influence NK cell activity during mAb treatment.
- To explore strategies for enhancing mAb therapy through T cell activation.
Main Methods:
- Co-culture of peripheral blood mononuclear cells with B cell lines (Raji) or autologous B cells in the presence of rituximab (RTX).
- Analysis of NK cell function (ADCC, viability, phenotype) and T cell involvement (contact-dependent, IL2 production).
- Assessment of other anti-CD20 and anti-EGFR antibodies, and the effect of T cell activation using anti-CD3/CD28 beads or bispecific antibodies.
- NK cell mRNA sequencing for pathway analysis.
Main Results:
- Rituximab (RTX) induced NK cell-mediated ADCC, enhanced NK cell viability, and modulated NK cell surface markers (CD56, CD16, CD57, KIR).
- T cells, particularly CD4+ T cells, mediated these RTX-induced NK cell changes in a contact-dependent manner, with IL2 playing a central role.
- T cell help was essential and not due to allogeneic reactions, as similar findings were observed with autologous B cells.
- Activation of small numbers of T cells significantly enhanced RTX-mediated NK cell ADCC, viability, and phenotypic changes.
- Pathway analysis indicated T cells maintain the viability of activated NK cells.
Conclusions:
- T cell help, primarily via local IL2 production, significantly contributes to NK cell ADCC and viability in anti-CD20 mAb therapy.
- Activating T cells within the tumor microenvironment holds potential for enhancing the efficacy of anti-CD20 and other mAb therapies.
- Strategies involving T cell activation, such as using anti-CD3 based bispecific antibodies, could overcome resistance and improve treatment outcomes.
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