The 51Cr‐release assay is mostly applied to detecting the cytotoxic activity of CD8+ T cells, and little is known about the activity of CD4+ T cells. Therefore, the correlation between the cytotoxic activity of CD4+ or CD8+ T cells and the incubation period with autologous tumor cells was analyzed by two methods. The incubation periods were 4 and 20 h (4 h and 20 h assay) for the 51Cr‐release assay. Eight pairs of tumor cells and T cells were assayed. T cells were fractionated into CD4+ and CD8+ T cells by using magnetic beads and panning methods, and those cells were activated by culture with recombinant interleukin‐2 and immobilized anti‐CD3 monoclonal antibody. In 6 out of 8 cases, no cytotoxic activity of CD4+ T cells was detected by the 4 h assay, whereas cytotoxic activity was detected in all cases in the 20 h assay. The cytotoxic activities in 20 h assay of CD4+ T cells were increased 67‐fold in comparison with the activities in 4 h assay (range: 5–197). In the case of CD8+ T cells, cytotoxic activities were detected in 6 out of 8 cases in the 4 h assay. The lytic unit ratio of CD4+ and CD8+ T cells was calculated as 1.5 in the 20 h assay (range: 0.2‐>7.2) versus 0.4 in the 4 h assay (range: < 0.1–1.3). Cytotoxic activities in colorimetric assay using Crystal Violet with a 24 h incubation were similar to those in the 20 h 51Cr‐release assay in all eight cases. These results indicate that CD4+ T cells have cytotoxic activity as strong as that of CD8+ T cells towards autologous tumor cells.
The coronavirus disease (COVID-19) pandemic has posed a major challenge to medical services worldwide. The causative agent-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-is a virus mainly transmitted via droplets and contact; however, data are emerging that support airborne transmission during aerosol-generating procedures, including endoscopy. Since almost 50% of COVID-19 patients exhibit detectable viral RNA in fecal samples, 1,2 there are still considerable concerns regarding viral transmission within endoscopic units, forcing endoscopists to implement strict precautions, such as a high threshold for endoscopy. 3 Indeed, the pandemic has had a significant global impact on endoscopic services, which is linked to the substantial reduction in capacity. 4 Using the UK National Endoscopy Database, Rutter et al. 5 analyzed the impact of the COVID-19 pandemic on endoscopic services, reporting that activity during the COVID-affected period had reduced to 12% of the pre-COVID level, and only 5% during the lowest period. Conversely, a recent detailed nominal analysis of the pandemic's impact on nonurgent endoscopic treatments-including peroral endoscopic myotomy (POEM)-may be informative and facilitate preparation for the upcoming resurge.Ominami et al. 6 analyzed the impact of COVID-19 on high-resolution manometry (HRM) and POEM for esophageal motility disorders (EMDs), including achalasia. The study was conducted across 14 Japanese high-volume centers with expertise in POEM, using a questionnaire survey. Since POEM should be specialized, intensified, and personalized due to the orphan entities of EMDs, the procedure is not widely distributed-even with Japanese precedence-and can only be performed at a limited number of facilities; cross-regional referrals have therefore been considerably frequent. They therefore confirmed for the first time that compared with 2019-just before the COVID-19 pandemic-HRM and POEM decreased by 17.2% (1587 to
Novel IL-2-binding molecules (p70 and p75) mediating internalization and degradation of IL-2 were examined by employing a human B lymphoblastoid line, SKW6-4 cells. High concentrations of IL-2 induced IgM secretion in these cells through a receptor distinct from Tac antigen. The acid-wash technique revealed that more than 60% of 125I-labeled IL-2 bound to the cells became acid-unremovable in the first 30 min of incubation at 37 degrees C and degradation products of 125I-IL-2 increased after 30 min of incubation. Treatment of the cells with NaN3 buffer inhibited the appearance of acid-unremovable 125I-IL-2, suggesting that acid-unremovable 125I-IL-2 was not due to fluid-phase pinocytosis but due to internalization. Loss of labeled bands by incubation of cells with 125I-IL-2 at 37 degrees C before affinity cross-linking demonstrated that 125I-IL-2 was internalized via novel IL-2-binding molecules. These results suggest that novel IL-2-binding molecules are responsible for internalization and may mediate signal transduction in B cells in the absence of Tac antigen.
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