Changes in light scatter properties are a general feature of cell death but are not characteristic of apoptotically dying cells

Triclosan induces apoptosis in Burkitt lymphoma-derived BJAB cells through caspase and JNK/MAPK pathways

Burkitt's lymphoma (BL) is the fastest growing human tumor. Current treatment consists of a multiagent regimen of cytotoxic drugs with serious side effjects including tumor lysis, cardiotoxicity, hepatic impairment, neuropathy, myelosuppression, increased susceptibility to malignancy, and death. Furthermore, therapeutic interventions in areas of BL prevalence are not as feasible as in high-income countries. Therefore, there exists an urgent need to identify new therapies with a safer profile and improved accessibility. Triclosan (TCS), an antimicrobial used in personal care products and surgical scrubs, has gained considerable interest as an antitumor agent due to its interference with fatty acid synthesis. Here, we investigate the antitumor properties and associated molecular mechanisms of TCS in BL-derived BJAB cells. Dose-dependent cell death was observed following treatment with 10-100 µM TCS for 24 h, which was associated with membrane phospholipid scrambling, compromised permeability, and cell shrinkage. TCS-induced cell death was accompanied by elevated intracellular calcium, perturbed redox balance, chromatin condensation, and DNA fragmentation. TCS upregulated Bad expression and downregulated that of Bcl2. Moreover, caspase and JNK MAPK signaling were required for the full apoptotic activity of TCS. In conclusion, this report identifies TCS as an antitumor agent and provides new insights into the molecular mechanisms governing TCS-induced apoptosis in BL cells.

Minimal residual disease monitoring cannot fully replace bone marrow morphology in assessing disease status in pediatric acute lymphoblastic leukemia

Minimal residual disease (MRD) monitoring has a strong prognostic value in childhood lymphoblastic leukemia (ALL) and is currently utilized in all major pediatric ALL protocols. MRD monitoring is done by multiparameter flow cytometry, IG/TCR quantitative PCR or reverse transcriptase quantitative PCR of leukemic fusion transcripts providing a reliable measurement of treatment response. However, occasionally bone marrow (BM) aspirates may not yield representative material or be misinterpreted due to treatment-induced changes in MRD marker profile, undetected subclones at diagnosis, contamination with peripheral blood or cell adhesion and stroma cell interactions posing a risk for underestimating MRD levels and misclassifying resistant disease that may be detected by traditional BM morphology methods, immunohistochemistry, karyotyping and FISH. We present four cases with high MRD levels where MRD monitoring failed to provide the correct stratification information. Through these cases, we discuss the continued need to consider all available information including BM smears, touch imprints and trephine biopsy preparations not only at diagnosis but throughout remission monitoring in pediatric ALL.

Evidence of perturbed germinal center dynamics, but preserved antibody diversity, in end-stage renal disease

INTRODUCTION

End-stage renal disease (ESRD) is associated with increased infectious susceptibility and with reduced vaccine responses consistent with compromised humoral immunity. Whether the compromised humoral immunity is due to reduced antibody diversity (reduced somatic hypermutation [SHM]) or altered germinal center (GC) dynamics is not known. The GC-derived chemokine CXCL13 as well as peripheral T follicular helper cells (pTFH) reflect GC dynamics, but have, similar to SHM, never been characterized in relation to ESRD.

METHODS

Serum CXCL 13 was determined by ELISA. PTFH were flow-cytometrically defined as CD4⁺ CD45RA^- CCR7⁺ CXCR5⁺ lymphocytes. Apoptotic lymphocyte subsets were in addition annexin V⁺. SHM was determined, by next-generation sequencing and bioinformatics, as nucleotide mutations within the IgG V_H (comprising the important antigen-binding domains of IgG, CDR1, and CDR2).

RESULTS

Elevated CXCL13 levels characterized ESRD (n = 19; [median] 90 pg/ml, P < 0.01) (controls, n = 18; 62 pg/ml). ESRD pTFH frequencies (n = 19; 11.6% [of CD4⁺ memory T cells], P < 0.02*, *Bonferroni corrected) (controls, n = 22; 14.9%) and concentrations (n = 19; 0.03 × 10⁹/L, P < 0.02*) (controls, n = 22; 0.07 × 10⁹/L) were reduced. ESRD pTFH were more apoptotic (n = 9; 25.7%, P = 0.04*) (controls, n = 10; 15.9%). SHM did not discriminate between ESRD (n = 10; 7.4%, P = 0.21) and controls (n = 10; 8.4%).

CONCLUSIONS

Elevated CXCL13 levels, reduced pTFH levels, and increased pTFH apoptosis suggest that perturbed GC dynamics, and not reduced antibody diversity, underlie the diminished vaccine responses and the compromised humoral immunity in ESRD. However, largely preserved SHM provides a rationale for pursuing vaccination in relation to ESRD.