In recent years, with the in-depth study of PD-1 and PD-L1 and the development of immunotherapy, the first problem is how to screen the beneficiaries. Recent clinical studies have shown that the expression level of PD-L1 in circulating tumor cells (CTC) can be used as a potential biomarker to play a guiding role in immunotherapy of malignant tumors. This article reviews the latest clinical research progress on the expression of PD-L1 in circulating tumor cells in various solid tumors.

Objective:To analyze the prevalence and clinical features of respiratory syncytial virus (RSV) in Chengde city.Methods:From August 2022 to June 2023, throat swabs and clinical data of 478 hospitalized children with respiratory tract infection in the Chengde Central Hospital were collected. Real-time quantitative PCR was used to detect the molecular epidemiology of RSV-A and RSV-B subtypes and analyze the clinical features of patients with RSV infection.Results:Among the hospitalized children, 67.57% (323/478) tested positive for RSV. The outbreak of RSV infection was caused by RSV-A subtype. The peaks of RSV-A infection occurred from November to December, 2022 and May to June, 2023. There were 86.07% (278/323) of the RSV-A-positive cases had mixed infection with other pathogens, primarily bacterial pathogens with Streptococcus pneumoniae being the most common, followed by Klebsiella pneumoniae. Influenza virus A was the most common viral pathogens causing mixed infection. The level of lactate dehydrogenase was higher in the patients with single RSV-A infection than in those with mixed infection ( Z=2.396, P=0.017), and higher than the normal upper limit. Compared with the single infection group, the mixed infection group had higher white blood cell count ( Z=2.417, P=0.016), neutrophil ratio ( Z=3.218, P=0.001), C-reactive protein level ( Z=1.998, P=0.046) and creatinine level ( Z=2.107, P=0.035), and lower lymphocyte ratio ( Z=3.205, P=0.001), but they were all within the normal range. There were no significant differences in the clinical features between RSV-A-positive patients co-infected with bacteria or other viruses (all P>0.05). Conclusions:RSV-A is the leading cause of respiratory tract infection in children in Chengde from 2022 to 2023, and often co-detected with bacteria. The mixed infection with other respiratory pathogens is related to the clinical features of patients with RSV-A infection.