Impact of Protein Kinase C Activation and Monoclonal Antibodies on Immune Checkpoint Regulation and B Cell Function in Patients with Chronic Lymphocytic Leukemia
<b>Background</b>: Chronic lymphocytic leukemia (CLL) is characterized by the proliferation of dysfunctional B cells, resulting in significant immune dysregulation. Patients with CLL exhibit varied responses to B cell receptor (BCR) targeted therapies, emphasizing the need for tailored i...
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2025-03-01
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| author | Aviwe Ntsethe Phiwayinkosi Vusi Dludla Bongani Brian Nkambule |
| author_facet | Aviwe Ntsethe Phiwayinkosi Vusi Dludla Bongani Brian Nkambule |
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| description | <b>Background</b>: Chronic lymphocytic leukemia (CLL) is characterized by the proliferation of dysfunctional B cells, resulting in significant immune dysregulation. Patients with CLL exhibit varied responses to B cell receptor (BCR) targeted therapies, emphasizing the need for tailored immunotherapy approaches. This study investigated B cell function in untreated patients with CLL, and we further explored the effects of ex vivo protein kinase C activation on immune checkpoint expression and B cell profiles. <b>Methods:</b> Peripheral blood samples were collected from 21 untreated patients with CLL at King Edward Hospital in South Africa, between 2019 and 2022. B cells were stimulated with phorbol myristate acetate (PMA) and ionomycin. Using flow cytometry, the study explored the levels of B cell subsets and immune checkpoint proteins programmed cell death 1 (PD-1), programmed cell death-ligand 1 (PD-L1), programmed cell death-ligand 2 (PD-L2) and cytotoxic T-lymphocyte associated protein 4 (CTLA-4) expression on various B cell subsets. <b>Results:</b> PMA and ionomycin B cell stimulation upregulated PD-1, CTLA-4 and PD-L2 expression on B cell subsets (<i>p</i> < 0.01). As expected, monoclonal antibodies targeting PD-1, PD-L1 and CTLA-4 significantly downregulated the CTLA-4 expression of B cell subsets (<i>p</i> < 0.05), while PD-L2 exhibited varied responses in different B cell subsets. Moreover, PD-1 and PD-L1 expression on total B cells significantly declined following their blockage (<i>p</i> < 0.01). In addition, these monoclonal antibodies increased the levels of CD19<sup>+</sup>CD27<sup>+</sup> B cells (<i>p</i> < 0.0128) and activated CD19<sup>+</sup>CD27<sup>+</sup> B cells (<i>p</i> < 0.01). <b>Conclusions:</b> Protein kinase C activation on B cells stimulates immune checkpoint expression. The use of monoclonal antibodies on B cells plays a critical role in the B cell function through the reduction in CD38 expressing activated B cells and upregulation of CD19<sup>+</sup>CD27<sup>+</sup> B cells. Moreover, the monoclonal antibody targeting PD-1, PD-L1 and CTLA-4 are effective in reducing the expression of CTLA-4 on B cell subsets, while PD-1 and PD-L1 blockage may be effective in reducing the expression of these immune checkpoints on total B cells. |
| format | Article |
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| publishDate | 2025-03-01 |
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| spelling | doaj-art-52ece9469fb64f749bc1b519ef37a4cd2025-08-20T02:42:42ZengMDPI AGBiomedicines2227-90592025-03-0113374110.3390/biomedicines13030741Impact of Protein Kinase C Activation and Monoclonal Antibodies on Immune Checkpoint Regulation and B Cell Function in Patients with Chronic Lymphocytic LeukemiaAviwe Ntsethe0Phiwayinkosi Vusi Dludla1Bongani Brian Nkambule2Department of Human Physiology, Nelson Mandela University, Gqeberha 6031, South AfricaDepartment of Biochemistry and Microbiology, University of Zululand, KwaDlangezwa 3886, South AfricaSchool of Laboratory Medicine and Medical Sciences (SLMMS), College of Health Sciences, University of KwaZulu-Natal, Durban 4000, South Africa<b>Background</b>: Chronic lymphocytic leukemia (CLL) is characterized by the proliferation of dysfunctional B cells, resulting in significant immune dysregulation. Patients with CLL exhibit varied responses to B cell receptor (BCR) targeted therapies, emphasizing the need for tailored immunotherapy approaches. This study investigated B cell function in untreated patients with CLL, and we further explored the effects of ex vivo protein kinase C activation on immune checkpoint expression and B cell profiles. <b>Methods:</b> Peripheral blood samples were collected from 21 untreated patients with CLL at King Edward Hospital in South Africa, between 2019 and 2022. B cells were stimulated with phorbol myristate acetate (PMA) and ionomycin. Using flow cytometry, the study explored the levels of B cell subsets and immune checkpoint proteins programmed cell death 1 (PD-1), programmed cell death-ligand 1 (PD-L1), programmed cell death-ligand 2 (PD-L2) and cytotoxic T-lymphocyte associated protein 4 (CTLA-4) expression on various B cell subsets. <b>Results:</b> PMA and ionomycin B cell stimulation upregulated PD-1, CTLA-4 and PD-L2 expression on B cell subsets (<i>p</i> < 0.01). As expected, monoclonal antibodies targeting PD-1, PD-L1 and CTLA-4 significantly downregulated the CTLA-4 expression of B cell subsets (<i>p</i> < 0.05), while PD-L2 exhibited varied responses in different B cell subsets. Moreover, PD-1 and PD-L1 expression on total B cells significantly declined following their blockage (<i>p</i> < 0.01). In addition, these monoclonal antibodies increased the levels of CD19<sup>+</sup>CD27<sup>+</sup> B cells (<i>p</i> < 0.0128) and activated CD19<sup>+</sup>CD27<sup>+</sup> B cells (<i>p</i> < 0.01). <b>Conclusions:</b> Protein kinase C activation on B cells stimulates immune checkpoint expression. The use of monoclonal antibodies on B cells plays a critical role in the B cell function through the reduction in CD38 expressing activated B cells and upregulation of CD19<sup>+</sup>CD27<sup>+</sup> B cells. Moreover, the monoclonal antibody targeting PD-1, PD-L1 and CTLA-4 are effective in reducing the expression of CTLA-4 on B cell subsets, while PD-1 and PD-L1 blockage may be effective in reducing the expression of these immune checkpoints on total B cells.https://www.mdpi.com/2227-9059/13/3/741chronic lymphocytic leukemiaimmune checkpoint inhibitorB cell subsetsionomycinphorbol myristate acetate |
| spellingShingle | Aviwe Ntsethe Phiwayinkosi Vusi Dludla Bongani Brian Nkambule Impact of Protein Kinase C Activation and Monoclonal Antibodies on Immune Checkpoint Regulation and B Cell Function in Patients with Chronic Lymphocytic Leukemia Biomedicines chronic lymphocytic leukemia immune checkpoint inhibitor B cell subsets ionomycin phorbol myristate acetate |
| title | Impact of Protein Kinase C Activation and Monoclonal Antibodies on Immune Checkpoint Regulation and B Cell Function in Patients with Chronic Lymphocytic Leukemia |
| title_full | Impact of Protein Kinase C Activation and Monoclonal Antibodies on Immune Checkpoint Regulation and B Cell Function in Patients with Chronic Lymphocytic Leukemia |
| title_fullStr | Impact of Protein Kinase C Activation and Monoclonal Antibodies on Immune Checkpoint Regulation and B Cell Function in Patients with Chronic Lymphocytic Leukemia |
| title_full_unstemmed | Impact of Protein Kinase C Activation and Monoclonal Antibodies on Immune Checkpoint Regulation and B Cell Function in Patients with Chronic Lymphocytic Leukemia |
| title_short | Impact of Protein Kinase C Activation and Monoclonal Antibodies on Immune Checkpoint Regulation and B Cell Function in Patients with Chronic Lymphocytic Leukemia |
| title_sort | impact of protein kinase c activation and monoclonal antibodies on immune checkpoint regulation and b cell function in patients with chronic lymphocytic leukemia |
| topic | chronic lymphocytic leukemia immune checkpoint inhibitor B cell subsets ionomycin phorbol myristate acetate |
| url | https://www.mdpi.com/2227-9059/13/3/741 |
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