Functional expression of CD73 on human natural killer cells.

The production of adenosine by CD73 on cancer cells in the tumor microenvironment is a recognized immunosuppressive mechanism contributing to immune evasion in many solid tumors. While NK cells have been purported to overexpress CD73 under certain conditions, this phenomenon has remained elusive and unclear. We have found that while NK cells are able to upregulate expression of CD73 on their surface when exposed to CD73+ cancer cells, this upregulation is not universal, nor is it often substantial. Rather, our data point to the extent of CD73 expression on NK cells to be both cancer-specific and environmentally-driven, and largely limited in intensity. We found that NK cell overexpression of CD73 responds to the level of CD73 on cancer cells and is enhanced in hypoxia. Interestingly, human CD73+ NK cells appear hyperfunctional in vitro compared to CD73- NK cells, suggesting that CD73 expression could be a bystander of NK cell activation. In addition, glioblastoma patient data show that tumor-infiltrating NK cells express CD73 variably, depending on donor, and present lower expression of CD16, alongside patient-specific changes in CEACAM1, CXCR3 and TIM-3, suggesting some functional changes in NK cell responses associated with expression of CD73 on NK cells in vivo. Taken together, our study is the first to show that while NK cells are largely resistant to the upregulation of CD73, CD73 expression is inducible on NK cells in response to CD73 on cancer cells, and these cells are associated with distinct functional signatures.

Validation of the Ask Suicide-Screening Questions for Adult Medical Inpatients: A Brief Tool for All Ages.

BACKGROUND: Few brief suicide risk screening instruments are validated for use in both adult and pediatric medical populations. Using the pediatric Ask Suicide-Screening Questions (ASQ) development study as a model, this study aimed to determine whether the ASQ is a valid suicide risk-screening instrument for use among adults medical patients, as well as to evaluate a set of other potential screening questions for use in adults. METHODS: Adult patients hospitalized on inpatient medical/surgical units from 4 hospitals were recruited to participate in a cross-sectional instrument-validation study. The 4-item ASQ and other candidate items were compared against the 25-item, previously validated Adult Suicidal Ideation Questionnaire as the criterion standard. RESULTS: A total of 727 adult medical inpatients completed the screening process. Compared with the Adult Suicidal Ideation Questionnaire, the ASQ performed best among the full set of candidate items, demonstrating strong psychometric properties, with a sensitivity of 100% (95% confidence interval = 90%-100%), a specificity of 89% (95% confidence interval = 86%-91%), and a negative predictive value of 100% (95% confidence interval = 99%-100%). A total of 4.8% (35/727) of the participants screened positive for suicide risk based on the standard criterion Adult Suicidal Ideation Questionnaire. CONCLUSIONS: The ASQ is a valid and brief suicide risk-screening tool for use among adults. Screening medical/surgical inpatients for suicide risk can be performed effectively for both adult and pediatric patients using this brief, primary screener.

Exploiting Femtoliter Microwells for the Sensitive Measurement of Protein Adsorption.

A method is described for the sensitive measurement of adsorbed proteins using femtoliter microwells. Quantitative measurement of adsorbed protein is demonstrated at surface densities from 10 fg/cm2 to 3 pg/cm2. Determination of the efficacy of barrier coatings is also demonstrated using femtoliter microwells. Adsorption at low surface densities is measured, indicating the highest affinity sites on the surface and therefore the initial stages of adsorption. The femtoliter microwell method is shown to be useful in detecting differences between effective protective coatings.

TIM-3 Expression Is Downregulated on Human NK Cells in Response to Cancer Targets in Synergy with Activation.

Among natural killer (NK) cell receptors, the T-cell immunoglobulin and mucin-containing domain (TIM-3) has been associated with both inhibitory and activating functions, depending on context and activation pathway. Ex vivo and in vitro, expression of TIM-3 is inducible and depends on activation stimulus. Here, we report that TIM-3 expression can be downregulated on NK cells under specific conditions. When NK cells are exposed to cancer targets, they synergize with stimulation conditions to induce a substantial decrease in TIM-3 expression on their surface. We found that such downregulation occurs following prior NK activation. Downregulated TIM-3 expression correlated to lower cytotoxicity and lower interferon gamma (IFN-γ) expression, fueling the notion that TIM-3 might function as a benchmark for human NK cell dysfunction.