Low-density PD-1 expression on resting human natural killer cells is functional and upregulated after transplantation.

Expression of programmed cell death protein 1 (PD-1) on natural killer (NK) cells has been difficult to analyze on human NK cells. By testing commercial clones and novel anti-PD-1 reagents, we found expression of functional PD-1 on resting human NK cells in healthy individuals and reconstituting NK cells early after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Peripheral blood samples from healthy individuals and transplant recipients were stained for PD-1 expression using the commercial anti-PD-1 clone PD1.3.1.3, fluorescein isothiocyanate (FITC)-labeled pembrolizumab, or an FITC-labeled single-chain variable fragment (scFv) reagent made from pembrolizumab. These reagents identified low yet consistent basal PD-1 expression on resting NK cells, a finding verified by finding lower PD-1 transcripts in sorted NK cells compared with those in resting or activated T cells. An increase in PD-1 expression was identified on paired resting NK cells after allo-HSCT. Blockade of PD-1 on resting NK cells from healthy donors with pembrolizumab did not enhance NK function against programmed death-ligand 1 (PD-L1)-expressing tumor lines, but blocking with its scFv derivative resulted in a twofold increase in NK cell degranulation and up to a fourfold increase in cytokine production. In support of this mechanism, PD-L1 overexpression of K562 targets suppressed NK cell function. Interleukin-15 (IL-15) activity was potent and could not be further enhanced by PD-1 blockade. A similar increase in function was observed with scFv PD-1 blockade on resting blood NK cells after allo-HSCT. We identify the functional importance of the PD-1/PD-L1 axis on human NK cells in which blockade or activation to overcome inhibition will enhance NK cell-mediated antitumor control.

Prevalence of comorbidities among individuals with COVID-19: A rapid review of current literature.

INTRODUCTION: On February 11, 2020 WHO designated the name "COVID-19" for the disease caused by "severe acute respiratory syndrome coronavirus 2" (SARS-CoV-2), a novel virus that quickly turned into a global pandemic. Risks associated with acquiring the virus have been found to most significantly vary by age and presence of underlying comorbidity. In this rapid literature review we explore the prevalence of comorbidities and associated adverse outcomes among individuals with COVID-19 and summarize our findings based on information available as of May 15, 2020. METHODS: A comprehensive systematic search was performed on PubMed, Medline, Scopus, Embase, and Google Scholar to find articles published until May 15, 2020. All relevant articles providing information on PCR tested COVID-19 positive patient population with clinical characteristics and epidemiological information were selected for review and analysis. RESULTS: A total of 27 articles consisting of 22,753 patient cases from major epicenters worldwide were included in the study. Major comorbidities seen in overall population were CVD (8.9%), HTN (27.4%), Diabetes (17.4%), COPD (7.5%), Cancer (3.5%), CKD (2.6%), and other (15.5%). Major comorbidity specific to countries included in the study were China (HTN 39.5%), South Korea (CVD 25.6%), Italy (HTN 35.9%), USA (HTN 38.9%), Mexico, (Other 42.3%), UK (HTN 27.8%), Iran (Diabetes 35.0%). Within fatal cases, an estimated 84.1% had presence of one or more comorbidity. Subgroup analysis of fatality association with having comorbidity had an estimated OR 0.83, CI [0.60-0.99], p<0.05. CONCLUSIONS: Based on our findings, hypertension followed by diabetes and cardiovascular diseases were the most common comorbidity seen in COVID-19 positive patients across major epicenters world-wide. Although having one or more comorbidity is linked to increased disease severity, no clear association was found between having these risk factors and increased risk of fatality.