Virus evolution and reduced viral viability during treatment of persistent COVID-19 Omicron BA.5 infection in an immunocompromised host.

We present the clinical course of a 72-year-old female with COVID-19 and a history of hematologic stem cell transplantation for acute myeloid leukemia. We performed serial analyses of viral load and whole-genome amplification. The virus growth was evaluated by a real-time polymerase chain reaction assay. Neutralizing activity was measured using a chemiluminescence reduction neutralizing test of SARS-CoV-2 pseudotyped virus. After neutralizing antibody therapy, the cycle threshold value of viral genome was 28. Viruses were no longer isolated in a cell culture. K129R, V722I, and V987F of amino acid mutation in spike protein region were identified, although they soon disappeared. Four months after symptom onset, E340K, K356R, R346T, and E484V mutations appeared and persisted. The viability of the virus decreased over time, with the virus at day 145 having a cycle threshold value of 24 and positive virus isolation, but at a slower growth rate. Neutralizing antibody activity for Omicron BA.5 finally appeared about 4 months after infection. In immunocompromised patients, persistent infection with amino acid mutations can occur without neutralizing antibodies. However, the production of neutralizing antibodies reduces the growth rate of the SARS-CoV-2. Moreover, infection control requires attention to viral dynamics and evolution under different conditions.

Frequent HLA-DR loss on hematopoietic stem progenitor cells in patients with cyclosporine-dependent aplastic anemia carrying HLA-DR15.

To determine whether antigen presentation by HLA-DR on hematopoietic stem progenitor cells (HSPCs) is involved in the development of acquired aplastic anemia (AA), we studied the HLA-DR expression on CD45dimCD34+CD38+ cells in the peripheral blood of 61 AA patients including 23 patients possessing HLA-class I allele-lacking (HLA-class I[-]) leukocytes. HLA-DR-lacking (DR[-]) cells accounted for 13.0-57.1% of the total HSPCs in seven (11.5%) patients with HLA-DR15 who did not possess HLA-class I(-) leukocytes. The incubation of sorted DR(-) HSPCs in the presence of IFN-γ for 72 h resulted in the full restoration of the DR expression. A comparison of the transcriptome profile between DR(-) and DR(+) HSPCs revealed the lower expression of immune response-related genes including co-stimulatory molecules (e.g., CD48, CD74, and CD86) in DR(-) cells, which was not evident in HLA-class I(-) HSPCs. DR(-) cells were exclusively detected in GPI(+) HSPCs in four patients whose HSPCs could be analyzed separately for GPI(+) and GPI(-) HSPCs. These findings suggest that CD4+ T cells specific to antigens presented by HLA-DR15 on HSPCs may contribute to the development of AA as well as the immune escape of GPI(-) HSPCs in a distinct way from CD8+ T cells recognizing HLA-class I-restricted antigens.

The GPI-anchored protein CD109 protects hematopoietic progenitor cells from undergoing erythroid differentiation induced by TGF-ß.

Although a glycosylphosphatidylinositol-anchored protein (GPI-AP) CD109 serves as a TGF-ß co-receptor and inhibits TGF-ß signaling in keratinocytes, the role of CD109 on hematopoietic stem progenitor cells (HSPCs) remains unknown. We studied the effect of CD109 knockout (KO) or knockdown (KD) on TF-1, a myeloid leukemia cell line that expresses CD109, and primary human HSPCs. CD109-KO or KD TF-1 cells underwent erythroid differentiation in the presence of TGF-ß. CD109 was more abundantly expressed in hematopoietic stem cells (HSCs) than in multipotent progenitors and HSPCs of human bone marrow (BM) and cord blood but was not detected in mouse HSCs. Erythroid differentiation was induced by TGF-ß to a greater extent in CD109-KD cord blood or iPS cell-derived megakaryocyte-erythrocyte progenitor cells (MEPs) than in wild-type MEPs. When we analyzed the phenotype of peripheral blood MEPs of patients with paroxysmal nocturnal hemoglobinuria who had both GPI(+) and GPI(-) CD34+ cells, the CD36 expression was more evident in CD109- MEPs than CD109+ MEPs. In summary, CD109 suppresses TGF-ß signaling in HSPCs, and the lack of CD109 may increase the sensitivity of PIGA-mutated HSPCs to TGF-ß, thus leading to the preferential commitment of erythroid progenitor cells to mature red blood cells in immune-mediated BM failure.

Detection of Antibodies Against Human Leukocyte Antigen Class II in the Sera of Patients Receiving Intravenous Immunoglobulin.

IVIG is occasionally used for preventing and treating severe infections of patients who are to undergo transplantation. Administration of IVIG, which includes high-titer antibodies (Abs) against HLA class I and II, might have a substantial influence on the HLA Ab test results of these patients. However, this issue has remained unreported. METHODS: Anti-HLA Ab titers were determined in 4 types of IVIG preparations, fresh frozen plasma, and the sera of 11 patients with hematological diseases before and after IVIG administration. RESULTS: Although anti-HLA Abs were not detected in any of the fresh frozen plasma products, various anti-HLA class I and II Abs were detected in all 4 IVIG preparations. Six out of 11 patients who had received IVIG showed a low titer of anti-HLA class II Abs, which were not detected before IVIG administration. Conversely, no anti-HLA class I Abs were detected in any of the 11 patients. Furthermore, all 4 (100%) patients who were positive for anti-HLA class II Abs initially and were assessable became negative for anti-HLA Abs after the discontinuation of IVIG treatment (median, d 79; range, d 22-192). CONCLUSIONS: IVIG preparations consist of high-titer anti-HLA class I and II Abs, but the latter can be transiently detected in the sera of patients who had received IVIG. When these patients are screened for the presence of donor-specific Abs, some may be incorrectly deemed positive for HLA class II Abs. Thus, caution is necessary when only donor-specific Abs specific to class II HLAs are detected in patients.

Potential mechanisms of nafamostat therapy for severe COVID-19 pneumonia with disseminated intravascular coagulation.

Nafamostat, a serine proteinase inhibitor with various actions including antithrombin, antiplasmin, and antitrypsin effects, has been used in clinical practice to treat disseminated intravascular coagulation (DIC) and pancreatitis. This case report describes the clinical course of a patient with COVID-19 pneumonia whose severe hypoxemia, probably caused by DIC and pulmonary embolism, showed remarkable improvement with combination heparin and nafamostat therapy. In addition, beneficial mechanisms of nafamostat against COVID-19 and the necessity of attention to hyperkalemia as an adverse effect are discussed.

Evaluation of a biosimilar granulocyte colony-stimulating factor for peripheral blood stem cell mobilization in Japanese healthy donors: a prospective study.

A "biosimilar" is a biotechnological product with a lower cost profile and equivalent efficacy and safety to the originator, but post-marketing clinical evaluation of biosimilar products has not been adequately conducted. We prospectively investigated the utility of biosimilar filgrastim in 13 peripheral blood stem cell (PBSC) donors from June 2014 to January 2017. In addition, we retrospectively compared these to another 13 PBSC donors mobilized with the originator filgrastim in the same period. Donor characteristics were equivalent between the groups. The median number of CD34+ cells per donor body weight (BW) and blood volume processed (BV) were 4.87 × 106/kg and 25.5 × 103/mL in the biosimilar group and 4.93 × 106/kg and 16.6 × 103/mL in the originator group, respectively. There were no significant differences between the groups in the number of CD34+ cells per donor BW or BV. All adverse events associated with G-CSF were permissive. The total G-CSF cost was significantly lower in the biosimilar group than in the originator group. These findings suggest that biosimilar filgrastim has the same efficacy and short-term safety as originator filgrastim for PBSC mobilization in healthy donors, with economic superiority. Longer follow-up studies are needed to evaluate the incidence of long-term adverse events.

Factors affecting performance of hospital infection control in Japan.

BACKGROUND: In Japan, hospital infection control (IC) programs are frequently underresourced, and their improvement is considered a pressing issue. METHODS: In 2005, we conducted a questionnaire survey of 638 teaching hospitals (most with 300 or more beds) and 882 nonteaching hospitals (most with fewer than 300 beds) in Japan. We analyzed associations among resources, infrastructures, activities, and performance related to IC. RESULTS: A total of 423 teaching hospitals (66.3%) and 377 nonteaching hospitals (50.2%) responded to the survey. The teaching hospitals had more IC infrastructure, such as full-time infection control practitioners (ICPs), link nurses, and infection control teams (ICTs), compared with the nonteaching hospitals. Infection surveillance was more likely to be implemented in hospitals with more ICP full-time equivalents (FTEs). IC performance scores were significantly higher in the teaching hospitals than in the nonteaching hospitals. In multivariate analyses, greater IC infrastructure, such as ICP FTEs, full-time IC nurses, and regular ICT rounds were significantly associated with IC performance. Hospital accreditation and hospital size also were significantly associated with higher IC performance scores. CONCLUSION: Given the strong associations found among IC infrastructure and performance, a new framework for evaluating IC infrastructure and for providing financial support may be effective in enhancing IC programs.

Impact of hospital accreditation on infection control programs in teaching hospitals in Japan.

BACKGROUND: In Japan, hospital infection control (IC) programs are frequently under-resourced, whereas their improvement is considered a pressing issue. Hospital accreditation may have a positive impact on IC program performance. The Japan Council for Quality Health Care (JCQHC) is a hospital accreditation organization that now prescribes broad elements of IC as part of its accreditation standards. METHODS: We sent questionnaire surveys to all teaching hospitals in Japan to characterize the current situation of hospital IC activities and identify the impact of accreditation on IC infrastructure and performance. The self-administered questionnaire that we used was developed based on the JCQHC accreditation standards. Surveys were sent to all institutions in 2004 and again in 2005. RESULTS: Of the 638 hospitals surveyed, 335 (52%) answered in both years. Most IC practitioners in Japanese teaching hospitals were working part time and spent limited hours performing IC duties. Surveillance was poorly implemented in Japan, and IC activities without evidence of effectiveness were widely performed. Surveillance was implemented more frequently in hospitals with adequate IC staffing. Improvement in IC infrastructure and performance between the surveys was larger in the newly accredited hospitals than the others. CONCLUSIONS: Hospital accreditation had a significant impact on hospitals' IC infrastructure and performance.