Lethal hit delivery by cytotoxic T lymphocytes (CTL) towards B lymphoma cells occurs as a binary, “yes/no” process. In non-hematologic solid tumors, however, CTL often fail to kill target cells during 1:1 conjugation. Here we describe a mechanism of “additive cytotoxicity” by which time-dependent integration of sublethal damage events, delivered by multiple CTL transiting between individual tumor cells, mediates effective elimination. Reversible sublethal damage includes perforin-dependent membrane pore formation, nuclear envelope rupture and DNA damage. Statistical modeling reveals that 3 serial hits delivered with decay intervals below 50 min discriminate between tumor cell death or survival after recovery. In live melanoma lesions in vivo, sublethal multi-hit delivery is most effective in interstitial tissue where high CTL densities and swarming support frequent serial CTL-tumor cell encounters. This identifies CTL-mediated cytotoxicity by multi-hit delivery as an incremental and tunable process, whereby accelerating damage magnitude and frequency may improve immune efficacy.

Background As of November 1, 2020, there have been more than 230K deaths and 9M confirmed and probable cases attributable to SARS-CoV-2 in the United States. However, this overwhelming toll has not been distributed equally, with geographic, race-ethnic, age, and socioeconomic disparities in exposure and mortality defining features of the U.S. COVID-19 epidemic. Methods We used individual-level COVID-19 incidence and mortality data from the U.S. state of Michigan to estimate age-specific incidence and mortality rates by race/ethnic group. Data were analyzed using hierarchical Bayesian regression models, and model results were validated using posterior predictive checks. Results In crude and age-standardized analyses we found rates of incidence and mortality more than twice as high than Whites for all groups except Native Americans. Blacks experienced the greatest burden of confirmed and probable COVID-19 infection (Age-standardized incidence = 1,626/100,000 population) and mortality (age-standardized mortality rate 244/100,000). These rates reflect large disparities, as Blacks experienced age-standardized incidence and mortality rates 5.5 (95% Posterior Credible Interval [CrI] = 5.4, 5.6) and 6.7 (95% CrI = 6.4, 7.1) times higher than Whites, respectively. We found that the bulk of the disparity in mortality between Blacks and Whites is driven by dramatically higher rates of COVID-19 infection across all age groups, particularly among older adults, rather than age-specific variation in case-fatality rates. Conclusions This work suggests that well-documented racial disparities in COVID-19 mortality in hard-hit settings, such as the U.S. state of Michigan, are driven primarily by variation in household, community and workplace exposure rather than case-fatality rates.

No abstract

We review the interaction between coronavirus disease (COVID-19) and coccidioidomycosis, a respiratory infection caused by inhalation of Coccidioides fungal spores in dust. We examine risk for co-infection among construction and agricultural workers, incarcerated persons, Black and Latino populations, and persons living in high dust areas. We further identify common risk factors for co-infection, including older age, diabetes, immunosuppression, racial or ethnic minority status, and smoking. Because these diseases cause similar symptoms, the COVID-19 pandemic might exacerbate delays in coccidioidomycosis diagnosis, potentially interfering with prompt administration of antifungal therapies. Finally, we examine the clinical implications of co-infection, including severe COVID-19 and reactivation of latent coccidioidomycosis. Physicians should consider coccidioidomycosis as a possible diagnosis when treating patients with respiratory symptoms. Preventive measures such as wearing face masks might mitigate exposure to dust and severe acute respiratory syndrome coronavirus 2, thereby protecting against both infections.

Allogeneic stem cell transplantation (allo-SCT) can induce remission in patients with hematological malignancies due to graft-versus-tumor (GVT) responses. This immune-mediated anti-tumor effect, however, is often accompanied by detrimental graft-versus-host disease (GVHD). Both GVT and GVHD are mediated by minor histocompatibility antigen (MiHA)-specific T cells recognizing peptide products from polymorphic genes that differ between recipient and donor. In this study, we evaluated whether mismatches in a panel of seventeen MiHA are associated with clinical outcome after partial T cell-depleted allo-SCT. Comprehensive statistical analysis revealed that DNA mismatches for one or more autosomal-encoded MiHA was associated with increased relapse-free survival in sibling transplants, (P =0.04), particularly in patients suffering from multiple myeloma (P =0.02). Moreover, mismatches for the ubiquitous Y chromosome-derived MiHA resulted in a higher incidence of acute GVHD (grade 3–4; P =0.004), while autosomal MiHA mismatches, ubiquitous or restricted to hematopoietic cells, were not associated with severe GVHD. Finally, we demonstrated considerable differences between MiHA in their capability to induce in vivo T cell responses using dual-color tetramer analysis of peripheral blood samples collected post-SCT. Importantly, detection of MiHA-specific T cell responses was associated with improved relapse-free survival in sibling transplants (P =0.01). Our findings provide a rationale to further boost GVT immunity towards autosomal MiHA with a hematopoietic restriction to improve outcome after HLA-matched allo-SCT.