Photochemical inactivation of lymphocytes by riboflavin with visible light for TA-GVHD prevention

UV-stimulated riboflavin exerts immunosuppressive effects in BALB/c mice and human PBMCs

Riboflavin (RF) as a photosensitizer has been used in corneal surgery and the inactivation of blood products. However, the effect of RF on immune cells after ultraviolet (UV) light stimulation has not been investigated. This study pioneered a novel application method of RF. Firstly, UV-stimulated RF was co-cultured with human peripheral blood mononuclear cells in vitro, and the apoptosis rate of lymphocyte subsets, cell proliferation inhibition rate and concentrations of IL-1β, IL-6, IL-10, TNF-α were assessed. UV-stimulated RF was then administered intravenously to mice via the tail vein for a consecutive period of 5 days. The levels of immunoglobulin (IgG, IgM, IgA), complement (C3, C4) and cytokines (IFN-γ, IL-4, IL17, TGF-β) were detected by ELISA. Flow cytometry was employed to analyze the populations of CD3+T, CD4+T, CD8+T and CD4+T/CD8+T cells in spleen lymphocytes of mice. The data showed that UV-stimulated RF can effectively induce apoptosis in lymphocytes, and different lymphocyte subtypes exhibited varying degrees of treatment tolerance. Additionally, the proliferative capacity of lymphocytes was suppressed, while their cytokine secretion capability was augmented. The animal experiments demonstrated that UV-stimulated RF led to a significant reduction observed in serum immunoglobulin and complement levels, accompanied by an elevation in IFN-γ, IL-17 and TGF-β levels, as well as a decline in IL-4 level. In summary, the results of both in vitro and in vivo experiments have demonstrated that UV-stimulated RF, exhibits the ability to partially inhibit immune function. This novel approach utilizing RF may offer innovative perspectives for diseases requiring immunosuppressive treatment.

Hypothermic storage of leukoreduced red blood cells for greater than 21 days is a safe alternative to irradiation

BACKGROUND

Irradiation of red blood cells (RBCs) inactivates residual donor T lymphocytes to prevent transfusion-associated graft-vs-host disease (TA-GVHD) but can have adverse effects on recipients and inventory management. Reported incidence of TA-GVHD is lower when leukoreduced RBCs and older blood products are transfused; therefore, the impact of leukoreduction and storage was evaluated as an alternative prevention strategy.

STUDY DESIGN AND METHODS

Effectiveness of leukoreduction filters on white blood cell (WBC) proliferation was evaluated by filtering buffy coat (BC) products and isolating residual WBCs. Additionally, leukoreduced RBCs were spiked with 5 × 10⁶ WBCs on Day 21 of hypothermic storage, then stored and processed on Days 7, 14, and 21 to obtain residual WBCs to investigate the impact of hypothermic storage on their viability and proliferative ability. Viability of residual WBCs was assessed by staining with annexin V and an antibody cocktail for flow cytometry analysis. Proliferative ability was assessed by placing carboxyfluorescein diacetate succinimidyl ester-labeled residual WBCs into culture for 6 days with phytohemagglutinin before flow cytometry assessment.

RESULTS

Filtration of BC units depleted WBCs, particularly T lymphocytes, to 0.001% ± 0.003% cells/unit, although proliferative activity remained consistent with prefiltration levels of WBCs. WBCs in stored RBCs remained viable even on Day 21 of storage; however, the proliferative activity decreased to 0.24% ± 0.41%.

CONCLUSIONS

Hypothermic storage of RBCs for 21 days or more is sufficient to inactivate T lymphocytes, which may help prevent TA-GVHD when irradiated RBCs are not available.

The Alleviative Effect of Vitamin B2 on Potassium Bromate-Induced Hepatotoxicity in Male Rats

Potassium bromate (PB) is a food enhancer, water disinfection by-product, and a proven carcinogen. It elicits toxicities in the living organism due to exposure and in a dose-dependent manner. The present study discourses the ameliorative efficacy of riboflavin (RF) in PB-administered rodents. The animals were distributed into five treatment groups: control (group I), PB alone (group II, 150 mg/kg), RF alone (group III, 2 mg/kg), PB+RF1 (group IV, 150 mg/kg + 2 mg/kg), and PB+RF2 (group V, 150 mg/kg + 4 mg/kg). After the round of the treatment, the animals were sacrificed to collect their blood and liver samples for the detailed analysis. Group II depicted perturbed liver functions evidenced by altered serum and toxicity markers along with the disturbed redox balance. Also, these biochemical results were found harmonious with histopathological analysis and comet assay. However, group III showed no noticeable alteration in the same parameters, whereas the combination groups (IV and V) exhibited dose-dependent amelioration in the PB-induced toxicities. Interestingly, RF favored apoptosis concomitant with suppressing the necrosis in the PB-challenged groups, as shown by the activity of caspase-3 and lactate dehydrogenase. Histopathological analysis and comet assay further consolidate these results. Hence, RF has significant alleviative property against PB-induced hepatotoxicity in vivo that can be used in the consumer items containing the toxicant.