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Background While we strive to live with SARS-CoV-2, defining the immune response that leads to recovery rather than severe disease remains highly important. COVID-19 has been associated with inflammation and a profoundly suppressed immune response. Objective To study myeloid-derived suppressor cells (MDSCs), which are potent immunosuppressive cells, in SARS-CoV-2 infection. Results Patients with severe and critical COVID-19 showed higher frequencies of neutrophilic (PMN)–MDSCs than patients with moderate illness and control individuals (P =.005). Severe disease in individuals older and younger than 60 years was associated with distinct PMN-MDSC frequencies, being predominantly higher in patients of 60 years of age and younger (P =.004). However, both age groups showed comparable inflammatory markers. In our analysis for the prediction of poor outcome during hospitalization, MDSCs were not associated with increased risk of death. Still, patients older than 60 years of age (odds ratio [OR] = 5.625; P =.02) with preexisting medical conditions (OR = 2.818; P =.003) showed more severe disease and worse outcome. Among the immunological parameters, increased C-reactive protein (OR = 1.015; P =.04) and lymphopenia (OR = 5.958; P =.04) strongly identified patients with poor prognosis. Conclusion PMN-MDSCs are associated with disease severity in COVID-19; however, MDSC levels do not predict increased risk of death during hospitalization. [ABSTRACT FROM AUTHOR]

Background: Caspase recruitment domain family, member 11 (CARD11) is an important protein which plays a fundamental role in the activation of NF-κβ pathway in lymphocytes. CARD11 deficiency can be inherited in either autosomal dominant or autosomal recessive forms and present with different phenotypes including combined immunodeficiency, atopic dermatitis, and other variable manifestations. The present report describes clinical phenotypes and immunological defects of two unrelated patients with missense homozygous variants in CARD11 presenting with combined immunodeficiency (CID) and atopic skin disease resembling that reported in dominant negative CARD11 deficiency. The patients underwent next generation sequencing, immunophenotyping of T and B subsets by flow cytometry, T cell stimulation, and evaluation of CARD11 expression. Results: Both patients had features suggesting CID including repeated pneumoniae with ICU admissions, chronic diarrhea, and itchy atopic skin disease. Patient-1 has homozygous missense variant in the C terminal domain (c.2839G > A, p.Glu947Lys), and patient-2 has homozygous variant in the inhibitory domain (c.1073C > G, p.Pro568Arg). Both have profound defects in Tregs with normal recent thymic emigrants, memory, and naïve CD4+ T cells. However, in response to stimulation, T cells failed to upregulate the expression of CD25. CARD11 expression by flow cytometry was decreased rather than abolished as previously described in patients with autosomal recessive CARD11 deficiency. B cells showed marked deficiency of switched memory and increase in transitional B cells. Conclusion: Missense variants causing CARD11 deficiency may affect the protein function rather than the expression and can result in a phenotype combining the atopic skin disease and the features of CID. [ABSTRACT FROM AUTHOR]