We have deeply investigated T cell compartment, plasma cytokines and cells producing cytokines in patients affected by Covid-19. At admission, patients were lymphopenic; in all of them SARS-CoV-2 was detected in a nasopharyngeal swab specimen by real-time RT-PCR, and pneumonia was subsequently confirmed by X-rays.Detailed 18-parameter flow cytometry was performed in 21 patients and 13 controls. Coupling polychromatic cytometry with unsupervised data analysis, we found that patients show an increased amount of CD4+ T lymphocytes that were activated, exhausted, stem memory or Treg. Similar results concerning activation and exhaustion were found in the CD8+ T cell compartment, within which the differences were even greater.Measuring plasma level of 31 cytokines linked to inflammation revealed that Covid-19 showed a dramatic increase of several molecules, such as TH1 and TH2 cytokines, chemokines, galectins, pro- and anti-inflammatory mediators, confirming the importance of a massive immune activation causing the cytokine storm. Then, intracellular staining detecting the simultaneous production of different cytokines after a para-physiologic stimulus given by anti-CD3/CD28 mAbs revealed not only a high capacity to produce a variety of molecules, including TNF-a, IFN-g and IL-2, but also a significant skewing of CD4+ T cells towards the TH17 phenotype.A therapeutic approach now exists based on the administration of drugs that block IL-6 pathway, and is now consistently improving the course of the disease. IL-17 is crucial in recruiting and activating neutrophils, cells that can migrate to the lung and are heavily involved in the pathogenesis of Covid-19. We show here that a significant skewing of activated T cells towards TH17 functional phenotype exists in Covid-19 patients. Thus, we suggest that blocking IL-17 pathway by already available biological drugs that are used to treat different pathologies could be a novel, additional strategy to improve the health of patients infected by SARS-CoV-2.

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Purpose People with hematologic malignancies have a significantly higher risk of developing severe and protracted forms of SARS-CoV-2 infection compared to immunocompetent patients, regardless of vaccination status. Results We describe two cases of prolonged SARS-CoV-2 infection with multiple relapses of COVID-19 pneumonia in patients with follicular lymphoma treated with bendamustine and obinutuzumab or rituximab. The aim is to highlight the complexity of SARS-CoV-2 infection in this fragile group of patients and the necessity of evidence-based strategies to treat them properly. Conclusions Patients with hematological malignancies treated with bendamustine and anti-CD20 antibodies had a significant risk of prolonged and relapsing course of COVID-19. Specific preventive and therapeutic strategies should be developed for this group of patients.

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