Profound dysregulation of T cell homeostasis and function in patients with severe COVID-19.

BACKGROUND: Coronavirus disease 2019 (COVID-19) is caused by infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and shows a broad clinical presentation ranging from asymptomatic infection to fatal disease. A very prominent feature associated with severe COVID-19 is T cell lymphopenia. However, homeostatic and functional properties of T cells are ill-defined in COVID-19. METHODS: We prospectively enrolled individuals with mild and severe COVID-19 into our multicenter cohort and performed a cross-sectional analysis of phenotypic and functional characteristics of T cells using 40-parameter mass cytometry, flow cytometry, targeted proteomics, and functional assays. RESULTS: Compared with mild disease, we observed strong perturbations of peripheral T cell homeostasis and function in severe COVID-19. Individuals with severe COVID-19 showed T cell lymphopenia and redistribution of T cell populations, including loss of naïve T cells, skewing toward CD4+ T follicular helper cells and cytotoxic CD4+ T cells, and expansion of activated and exhausted T cells. Extensive T cell apoptosis was particularly evident with severe disease and T cell lymphopenia, which in turn was accompanied by impaired T cell responses to several common viral antigens. Patients with severe disease showed elevated interleukin-7 and increased T cell proliferation. Furthermore, patients sampled at late time points after symptom onset had higher T cell counts and improved antiviral T cell responses. CONCLUSION: Our study suggests that severe COVID-19 is characterized by extensive T cell dysfunction and T cell apoptosis, which is associated with signs of homeostatic T cell proliferation and T cell recovery.

Recurrent hypoglycaemia in HIV-positive narcotic addicts.

QUESTIONS UNDER STUDY: We describe two narcotic addict women with recurrent hypoglycaemic episodes. In both patients, hyperinsulinaemic hypoglycaemia occurring in the fasting state was documented and computed tomography of the pancreas was normal. METHODS AND RESULTS: In patient 1, selective arterial calcium stimulation with hepatic venous sampling (ASVS) revealed pronounced insulin hypersecretion predominantly in the tail and, to a lesser extent, in the corpus and the head of the pancreas. On laparoscopic exploration, tumours could not be detected be it grossly or by intraoperative ultrasound. Distal pancreatectomy was performed laparoscopically, and histological examination of the resected tissue revealed nesidioblastosis. ASVS was also performed in patient 2 revealing less marked increases in insulin secretion, ie up to 2.3-fold in response to calcium stimulation of the superior mesenteric artery, consistent with the presence of pathological beta-cells located predominantly in the head of the pancreas. Surgical exploration was not performed in this patient. CONCLUSION: HIV infection had been known in both women for around ten years and both patients were not on antiretroviral therapy. Because symptomatic nesidioblastosis in adult patients is a very rare disorder, we speculate that nesidioblastosis may develop in the context of HIV infection and/or abuse of narcotic drugs. Our observations illustrate that neurocognitive impairment in HIV positive patients is not always due to toxic compounds or a cerebral disorder but may be caused by an apparently rare pancreatic disorder, nesidioblastosis. Thus, the patients should be checked for the presence of hyperinsulinaemic hypoglycaemia.