COVID‐19 is a disease characterized by acute respiratory failure and is a major health problem worldwide. Here, we aimed to investigate the role of CD39 expression in Treg cell subsets in COVID‐19 immunopathogenesis and its relationship to disease severity. One hundred and ninety COVID‐19 patients (juveniles, adults) and 43 volunteers as healthy controls were enrolled in our study. Flow cytometric analysis was performed using a 10‐color monoclonal antibody panel from peripheral blood samples. In adult patients, CD39⁺ Tregs increased with disease severity. In contrast, CD39⁺ Tregs were decreased in juvenile patients in an age‐dependent manner. Overall, our study reveals an interesting profile of CD39‐expressing Tregs in adult and juvenile cases of COVID‐19. Our results provide a better understanding of the possible role of Tregs in the mechanism of immune response in COVID‐19 cases.

Önemli transfüzyon komplikasyonlardan biri olan transfüzyonla ilişkili immün düzenlenme (TRIM), allojeneik kan transfüzyonunun (AKT) alıcının immün sisteminde yol açtığı değişiklikler olarak tanımlanabilir. En çok suçlanan etken, kan bileşeni içindeki mononükleer (MNH) hücrelerdir. Bu nedenle çalışmamızda eritrosit süspansiyonları (ES) içindeki T hücreler (CD3+CD4+ ve CD3+CD8+) hedeflenmiş, depolama koşullarının etkisiyle canlılık, proliferasyon ve aktivasyon düzeylerindeki değişimler incelenmiştir. Bu amaçla, üç adet kan bağışçısından alınan tam kanlardan ES’ler elde edilmiştir. Her kan bileşeninden tam kan örneği (5. saat) ve ES örnekleri (0, 7, 14, 21, 42. gün) elde edilmiştir. Ayrıca bağışçıdan bağış öncesi EDTA’lı tüplere alınan iki adet örnek de çalışmaya katılmıştır. Analizler bu örneklerden ayrıştırılan MNH kullanılarak yapılmıştır. Canlılık analizleri doğrudan MNH’ler, proliferasyon ve aktivasyon analizleri MNH kültürleri aracılığıyla akan hücre ölçerde gerçekleştirilmiştir. Canlılık düzeylerinin depolama süresi ortalarında azalmaya başladığı, 42. gün ES örneklerinde hemen tamamen yok olduğu belirlenmiştir. T hücrelerin proliferasyon becerisi daha erken azalmış ve 21. gün ES örneklerinde kaybolmuştur. Aktivasyon belirteci düzeyleri MNH kültürünün sıfırıncı saatlerine göre 16 ve 72 saatlerde artış göstermiştir. Ayrıca bağışçıların yaşlarına göre de sonuçlarda belirgin farklılıklar gözlemlenmiştir. Sonuç olarak ES depolama süresi ve koşullarının etkisiyle ürün içindeki T lenfositlerin canlılığı ve proliferasyon becerileri azalmaktadır. Bu sonuçlar allojeneik T lenfositlerin TRIM gelişimiyle ilişkilerinin düşük olabileceğini; T lenfosit aktivasyon kapasitelerinin ES’den uzaklaştıklarında artmış göstermesi eritrositlerin baskılayıcı özellik gösterebildiğini; TRIM gelişiminde bağışçı ve hasta yaşı gibi demografik parametrelerin de rol oynayabileceğini düşündürmektedir.

Background/Objectives: Our study was designed to explore the potential role of allogeneic CD8⁺ T lymphocytes present in red blood cell concentrates (RBCs) in the development of transfusion-related immunomodulation (TRIM) and the effect of storage time on these cells. Methods: From six units of whole blood, donated by volunteers, RBCs were obtained and each one was divided into three equal parts to provide the samples for storage days 0, 21, and 42. On related days, mononuclear cells (MNCs) were isolated from these RBC samples. MNCs were cultured, and phytohemagglutinin was added to half of the culture wells to stimulate the cells and achieve T cell division. Supernatants and MNCs were obtained from stimulated (STI) and unstimulated (US) wells. Supernatants were used for cytokine analyses, while MNCs were used to investigate the T cells and transcription factors. Results: The frequency of CD8⁺ T lymphocytes (Tc), their subgroups (Tc1, Tc2, and Tc17), specific transcription factors, and effector cytokines decreased during the storage time, but cell viability increased. CD3⁺CD8⁺TNF-α+ cells were significantly higher in the STI group on day 0 compared to the US group. Other cells did not respond to the mitogen (phytohemagglutinin) stimulation. Conclusions: During storage, the number of Tc cells and their ability to respond to mitogens decreased over time. The unresponsiveness was not recovered in ex vivo cell culture. Our findings suggest that transfused Tc cells are unlikely to be primary mediators of TRIM.

Buffy-Coat concentrates (BFCs) can be transfused to provide neutrophil support in patients with febrile neutropenia. In this study, the oxidative burst capacity of neutrophils in BFC was investigated in 12 hours-stored BFCs (n=16). Samples taken from healthy volunteers (n=7) (fresh EDTA; fEDTA) and taken before donation from blood donors who donated BFCs (n=16) (donor EDTA; dEDTA) were included. fEDTA and dEDTA samples were used to compare the effect of time. Nitroblue tetrazolium (NBT) test was performed to evaluate the oxidative burst. Different titrations (1:16, 1:32, 1:64, 1:128) of phorbol myristate acetate (PMA) were used. BFC samples without PMA addition were used as negative control (NC). While similar results were obtained in BFC samples with fEDTA samples in NC, oxidative activity was statistically high in the dEDTA samples. These results suggested that neutrophils in dEDTA may be spontaneously activated. In all PMA titrations except 1:64 PMA titers, the oxidative burst capacity in dEDTA and BFC samples was significantly lower than that in fEDTA samples. Also, oxidative burst significantly decreased in fEDTA-dEDTA-BFC in all PMA titrations. Spontaneous burst was detected in dEDTA samples under PMA-free conditions, but not in BFC samples, indicating that the additive solution in BFC protected neutrophils from spontaneous activation. Despite the statistically significant decrease, neutrophils in BFCs can remain functional due to their high oxidative activity at all titers (above 75%). This indicates that they can function when transfused. This result also shows that we can use BFCs as a source of neutrophils in experiments.