Preferential Induction of B Cell Apoptosis Using Photodynamic Therapy.
Bibliographic record
Abstract
Abstract Apoptotic cell death in cancer cells promotes antigen presentation and favors the development of an anti-tumor vaccination effect. While lymphoma cells can easily be obtained from lymph nodes or peripheral blood, these malignant cells usually co-localize with normal hematopoietic T lymphocytes, rendering the selective induction of apoptosis in malignant B cells particularly difficult. We have found that photodynamic therapy (PDT) using the photosensitizer 4–5 dibromorhodamine methyl ester (TH9402) and visible light (514 nm) can be used to preferentially eliminate malignant B-lineage non-Hodgkin’s lymphoma cells (mean of 3–4 logs) over T lymphocytes. As a rhodamine derivative, TH9402 cellular efflux is mediated through the P-glycoprotein (Pgp) pump. However, the preferential elimination of B cells over resting T cells could not be ascribed to Pgp inactivation and we found no difference in intracellular retention of TH9402 between B and T cells. In order to understand the molecular events leading to such high B cell susceptibility to PDT, we then investigated the nature of death pathways involved. To determine whether apoptosis was the preponderant mechanism leading to the rapid elimination of B cells, we measured the binding of Annexin V (AnnV) in 7-aminoactinomycin D (7AAD) negative (i.e. live) B and T cells using flow cytometry, and quantified DNA fragmentation and caspase 3 and 9 activity in isolated CD3+ and CD19+ PDT treated and untreated cells. We found that B cells demonstrated high levels of apoptosis after PDT, with 53±1.3% (mean±SE) AnnexinV+/7AAD- cells compared to 30±1.9% in T cells (p< 0.05). The extent of DNA fragmentation, as determined by the TUNEL reaction, was extensive in B cells (33.7±9.8%)(mean±SE) but not T cells (2.3±0.1%) when measured at 4 hours post PDT (p<0.01). After PDT, catalytic caspase 3 levels were also 4-fold higher in CD19+ cells than CD3+ cells (p<0.01). In contrast, caspase 9 levels remained low for both cell types. The induction of apoptosis translated into the elimination of more than 90% of B cells within 4 hours after PDT, while the majority of T cells were not affected. Importantly, similar elimination of B-lineage cell lines and patient cells was observed, using a limiting dilution assay, whether cells overexpressed the anti-apoptotic bcl-2 protein or not. Thus, these results indicate that the predominant caspase 3 apoptotic pathway is specifically implicated in PDT-induced B cell death, and its early activation explains the rapid and profound sensitivity of B lymphocytes to PDT. This strategy could promote tumor cell vaccination in the context of autologous TH9402-purged stem cell transplantation for patients with B-lineage malignancies. In addition, preferential B cell targeting could take advantage of the crucial immunomodulatory role of apoptosis for the treatment of patients with autoimmune B cell disorders.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".