Evaluation of Molecular-level Changes of Programmed Cell Death Ligand-1 after Radiation Therapy in a BALB/c CT26 Colorectal Mouse Tumor Model.

The effects of radiation therapy (RT) for cancer can be systemic and partially mediated by the immune system. However, radiation alone is unlikely to transform an immunosuppressive environment into an immunostimulatory one. Therefore, an effective combination of RT and immunotherapy may provide a new, more efficient treatment approach. Here, we investigated how the expression of programmed cell death-ligand 1 (PD-L1) in the tumor microenvironment varied in different RT regimens with the same biologically effective dose. In this study, female BALB/c mice inoculated with CT26 tumor cells were irradiated with 3 different RT regimens using the same BED of 40 gray (Gy). These included ablative RT (1*15 Gy), hypo-fractionated RT (2*10 Gy), and conventional (Hyper-fractionated) RT (10*3 Gy). PD-L1 expression was analyzed with immunohistochemical staining on days 2 and 20 and when the size of tumors had reached 2 cm2 after RT. All treated groups expressed PD-L1, but the group receiving single ablative high-dose RT showed higher expression compared to the other groups. No significant differences in PD-L1 expression were observed at different times in the same group. These findings showed that different regimens of RT have different effects on the TME, so a combination of RT and immune checkpoint blockade could be clinically used in cancer patients.

Serological assay for anti-SARS-CoV-2 antibodies improves sensitivity of diagnosis of COVID-19 patients.

The emergence of SARS-CoV-2, responsible for coronavirus disease-2019 (COVID-19), has become a major global health problem. The molecular testing is the accepted assay in SARS-CoV-2 detection. However, there are several reasons for low sensitivity by RNA detection, causing challenges in SARS-CoV-2 diagnosis. In this study, we aimed to investigate serological patterns of SARS-CoV-2 specific IgM, and IgG in 111 hospitalized, and 34 recovered COVID-19 patients and 311 prepandemic normal serum specimens by ELISA. The validity of the ELISA kits was evaluated using samples from normal and recovered cases. This showed that 98.1%, and 98.4% of prepandemic normal samples were negative for anti-SARS-CoV-2 IgM, and IgG, respectively. Assessment of 34 COVID-19 confirmed recovered patients showed a test sensitivity of 76.5%, and 94.1% for IgM, and IgG, respectively. In COVID-19 hospitalized patients, 42.3%, and 51.4% were positive for IgM and IgG, respectively. Viral RNA was not detectable in 43.3% of the hospitalized patients. Interestingly, combined molecular and serological testing improved the sensitivity of COVID-19 diagnosis to 79.6%. Using PCR with combined IgM/IgG results augmented the patient diagnosis sensitivity to 65.3% and 87.2% in ≤ 7 days, and > 7 days intervals, respectively. Overall, serological tests in combination with PCR can improve the sensitivity of COVID-19 diagnosis.

Prevalence of Anti-SARS-CoV-2 Specific Antibodies in Health-Care Workers Compared to General Population during an Early Phase of the Pandemic, Tehran-Iran.

BACKGROUND: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) rapidly transmits in general population, mainly between health-care workers (HCWs) who are in close contact with patients. OBJECTIVE: To study the seropositivity of HCWs as a high-risk group compared to general population. METHODS: 72 samples were obtained from HCWs working in Masih Daneshvari hospital as one of the main COVID-19 admission centers in Tehran, during April 4 to 6, 2020. Also we collected 2021 blood samples from general population. The SARS-CoV-2 specific IgM, and IgG antibodies in the collected serum specimens were measured by commercial ELISA kits. RESULTS: Based on the clinical manifestations, 25.0%, 47.2%, and 27.8% of HCWs were categorized as symptomatic with typical symptoms, symptomatic with atypical symptoms, and asymptomatic, respectively. Symptomatic individuals with typical and atypical symptoms were 63.2% and 36.8% positive in RT-PCR test, respectively. Anti-SARS-CoV-2 IgM and IgG antibodies were detected in 15.3% and 27.8% of HCWs samples, respectively. Antibody testing in the general population indicated that SARS-CoV-2 specific IgM and IgG were found in (162/2021) 8%, and (290/2021) 14.4%, respectively. The frequency of positive cases of IgM and IgG were significantly increased in HCWs compared to general population (p= 0.028 for IgM and p= 0.002 for IgG). CONCLUSION: The frequency of SARS-CoV-2 specific antibodies in HCWs was higher than general population indicating a higher viral transmission via close exposure with COVID-19 patients.