In patients infected by SARS-CoV-2 who experience an exaggerated inflammation leading to pneumonia, monocytes likely play a major role but have received poor attention. Thus, we analyzed peripheral blood monocytes from patients with COVID-19 pneumonia and found that these cells show signs of altered bioenergetics and mitochondrial dysfunction, had a reduced basal and maximal respiration, reduced spare respiratory capacity, and decreased proton leak. Basal extracellular acidification rate was also diminished, suggesting reduced capability to perform aerobic glycolysis. Although COVID-19 monocytes had a reduced ability to perform oxidative burst, they were still capable of producing TNF and IFN-c in vitro. A significantly high amount of monocytes had depolarized mitochondria and abnormal mitochondrial ultrastructure. A redistribution of monocyte subsets, with a significant expansion of intermediate/pro-inflammatory cells, and high amounts of immature monocytes were found, along with a concomitant compression of classical monocytes, and an increased expression of inhibitory checkpoints like PD-1/PD-L1. High plasma levels of several inflammatory cytokines and chemokines, including GM-CSF, IL-18, CCL2, CXCL10, and osteopontin, finally confirm the importance of monocytes in COVID-19 immunopathogenesis.

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Mucorales-specific T cells were investigated in 28 hematologic patients during the course of their treatment. Three developed proven invasive mucormycosis (IM), 17 had infections of known origin but other than IM, and 8 never had fever during the period of observation. Mucorales-specific T cells could be detected only in patients with IM, both at diagnosis and throughout the entire course of the IM, but neither before nor for long after resolution of the infection. Such T cells predominantly produced IL-4, IFN-γ, IL-10, and to a lesser extent IL-17 and belonged to either CD4+ or CD8+ subsets. The specific T cells that produced IFN-γ were able to directly induce damage to Mucorales hyphae. None of the 25 patients without IM had Mucorales-specific T cells. Specific T cells contribute to human immune responses against fungi of the order Mucorales and could be evaluated as a surrogate diagnostic marker of IM.

Posttransplantation human herpesvirus-8 (HHV8)/Kaposi sarcoma herpesvirus (KSHV) primary infection and/or reactivations are associated with uncommon and sometimes fatal, neoplastic, and nonneoplastic diseases. HHV8-related clinical manifestations notably range from Kaposi sarcoma (KS) to either primary effusion lymphoma or multicentric Castleman disease B-cell malignancies, and from polyclonal HHV8-positive plasmacytic lymphoproliferative disorders to bone marrow failure and peripheral cytopenias, associated or not with hemophagocytic syndromes, and to acute hepatitis syndromes. We reviewed the patient series reported in the literature and summarized clinical management aspects, in terms of diagnosis, follow-up, and treatment. We described typical clinical presentations and histopathologic diagnostic features of these diseases, and we discussed the role of HHV8-specific serologic, molecular, and immunologic assays, particularly focusing on recent data from HHV8-specific T-cell monitoring in posttransplantation KS patients. We finally discussed actual therapeutic options, namely, the reduction or discontinuation of immunosuppressive therapy or the switch from calcineurin inhibitors to mTOR inhibitors, as alternatives to antineoplastic chemotherapy, along with the use of antiherpesvirus agents as prophylactic or therapeutic measures, and treatment with rituximab in posttransplantation multicentric Castleman disease patients and non-neoplastic HHV8-associated syndromes. IntroductionHerpesvirus-associated hematologic diseases often represent primary clinical challenges during the multidisciplinary follow-up of posttransplant patients, either with hematopoietic stem cell transplant (HSCT) or with solid organ transplant (SOT). In immunosuppressed organ recipients, latent human ␥-herpesvirus, namely, EBV and human herpesvirus-8 (HHV8)/Kaposi sarcoma herpesvirus (KSHV) are typically responsible for several virus-driven neoplastic proliferations, as well as they may sometimes cause uncommon, but equally life-threatening, non-neoplastic infectious complications. During the past decade, large amounts of experimental evidence have come out on these topics, and some of them have yet begun to influence the clinical behavior, in terms of diagnosis and treatment. Chiefly, EBV-related complications have been extensively studied and discussed, so that now physicians can rely on accurate and updated clinical recommendations, in particular dealing with early diagnosis, monitoring and treatment of EBV ϩ posttransplantation lymphoproliferative diseases (PTLDs). 1 With regards to HHV8, practical management of the virus-associated neoplastic lymphoproliferations has deeply been revised in HIVpositive subjects, 2,3 whereas in SOT and HSCT settings, the diagnostic and therapeutic issues about the various HHV8-driven manifestations (either neoplastic or non-neoplastic) are only occasionally reported in the literature, but most of these diseases revealed to be rapidly lethal if not timely recognized and adequately treated. Indeed, posttra...

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