T cell immunity is central for the control of viral infections. To characterize T cell immunity, but also for the development of vaccines, identification of exact viral T cell epitopes is fundamental. Here we identify and characterize multiple dominant and subdominant SARS-CoV-2 HLA class I and HLA-DR peptides as potential T cell epitopes in COVID-19 convalescent and unexposed individuals. SARS-CoV-2-specific peptides enabled detection of post-infectious T cell immunity, even in seronegative convalescent individuals. Cross-reactive SARS-CoV-2 peptides revealed pre-existing T cell responses in 81% of unexposed individuals and validated similarity with common cold coronaviruses, providing a functional basis for heterologous immunity in SARS-CoV-2 infection. Diversity of SARS-CoV-2 T cell responses was associated with mild symptoms of COVID-19, providing evidence that immunity requires recognition of multiple epitopes. Together, the proposed SARS-CoV-2 T cell epitopes enable identification of heterologous and post-infectious T cell immunity and facilitate development of diagnostic, preventive and therapeutic measures for COVID-19. NATURE IMMUNOLOGY | www.nature.com/natureimmunology Articles NATuRE ImmuNOLOgy evidence that antibody responses are short-lived and can even cause or aggravate virus-associated lung pathology 16,17. With regard to SARS-CoV-2, very recent studies 18-20 described CD4 + and CD8 + T cell responses to viral peptide megapools in donors that had recovered from COVID-19 and individuals not exposed to SARS-CoV-2, the latter being indicative of potential T cell cross-reactivity 21,22. The exact viral epitopes that mediate these T cell responses against SARS-CoV-2, however, were not identified and characterized in detail in these studies, but are prerequisite (1) to delineate the role of post-infectious and heterologous T cell immunity in COVID-19, (2) for establishing diagnostic tools to identify SARS-CoV-2 immunity and, most importantly, (3) to define target structures for the development of SARS-CoV-2-specific vaccines and immunotherapies. In this study, we define SARS-CoV-2-specific and cross-reactive CD4 + and CD8 + T cell epitopes in a large collection of SARS-CoV-2 convalescent as well as nonexposed individuals and their relevance for immunity and the course of COVID-19 disease. Results Identification of SARS-CoV-2-derived peptides. A new prediction and selection workflow, based on the integration of the algorithms SYFPEITHI and NetMHCpan, identified 1,739 and 1,591 auspicious SARS-CoV-2-derived HLA class I-and HLA-DR-binding peptides across all ten viral open-reading frames (ORFs) (Fig. 1a and Extended Data Fig. 1a,b). Predictions were performed for the ten and six most common HLA class I

Triple-negative breast cancers (TNBC), characterized by absence of estrogen receptor (ER), progesterone receptor (PR) and lack of overexpression of human epidermal growth factor receptor 2 (HER2), are typically associated with poor prognosis, due to aggressive tumor phenotype(s), only partial response to chemotherapy and present lack of clinically established targeted therapies. Advances in the design of individualized strategies for treatment of TNBC patients require further elucidation, by combined 'omics' approaches, of the molecular mechanisms underlying TNBC phenotypic heterogeneity, and the still poorly understood association of TNBC with BRCA1 mutations. An overview is here presented on TNBC profiling in terms of expression signatures, within the functional genomic breast tumor classification, and ongoing efforts toward identification of new therapy targets and bioimaging markers. Due to the complexity of aberrant molecular patterns involved in expression, pathological progression and biological/clinical heterogeneity, the search for novel TNBC biomarkers and therapy targets requires collection of multi-dimensional data sets, use of robust multivariate data analysis techniques and development of innovative systems biology approaches.

Psoriasis is an inflammatory skin disease with strong neutrophil (PMN) infiltration and high levels of the antimicrobial peptide, LL37. LL37 in complex with DNA and RNA is thought to initiate disease exacerbation via plasmacytoid dendritic cells. However, the source of nucleic acids supposed to start this initial inflammatory event remains unknown. We show here that primary murine and human PMNs mount a fulminant and self-propagating neutrophil extracellular trap (NET) and cytokine response, but independently of the canonical NET component, DNA. Unexpectedly, RNA, which is abundant in NETs and psoriatic but not healthy skin, in complex with LL37 triggered TLR8/TLR13-mediated cytokine and NET release by PMNs in vitro and in vivo. Transfer of NETs to naive human PMNs prompts additional NET release, promoting further inflammation. Our study thus uncovers a self-propagating vicious cycle contributing to chronic inflammation in psoriasis, and NET-associated RNA (naRNA) as a physiologically relevant NET component.