Patients with Covid-19 exhibit different immunological profiles according to their clinical presentation.

OBJECTIVES: A novel beta coronavirus has been identified as responsible for the 2019 coronavirus infection (Covid-19). Clinical presentations range from asymptomatic cases to acute respiratory distress syndrome with fatal outcome. Such a broad spectrum of disease expression calls for an investigation of immune response characteristics. METHODS: We identified subjects admitted for Covid-19 in whom a large panel of immunological markers were measured, including B- and T- and NK-lymphocyte phenotypes, T-lymphocyte subpopulation cells and plasma cytokines. Patients were divided according to symptom severity during hospitalisation, in those with uncomplicated and complicated infection. Differences between groups were analyzed. RESULTS: Seventeen patients were included (mean age: 83 years; 9 women; mean delay of symptoms onset: 4 days). Six had uncomplicated infection, while 11 developed complicated forms during hospitalization. CD10 + B lymphocyte levels were inversely correlated with clinical severity (5.8% vs 2.0%, p = 0.04) and CD10+ levels above 3% were independently associated with uncomplicated forms [Odds Ratio 0.04 (CI 0.002-0.795, p = 0.034)]. TNF-alpha, IL-1, Il-6 and Il-8 measurements upon admission differed between patients who died and those who survived (p < 0.01 for all comparisons). CONCLUSIONS: In a population of elderly patients recently infected with Covid-19, CD10 + B cell levels were inversely correlated with clinical severity. Cytokine values upon admission were highly predictive of fatal outcome during hospitalisation. These findings could explain differences in the clinical presentation and allow rapid identification of patients at risk for complications.

Functional immune assay using interferon-gamma could predict infectious events in end-stage kidney disease.

BACKGROUND: Infections remain the second most common cause of death in patients with end-stage kidney disease (ESKD). We aimed to evaluate non-specific cell-mediated immunity in an ESKD cohort using a functional assay applicable to routine use, QuantiFERON-Monitor (Qiagen), and assess whether it can predict infectious events. METHODS: In this prospective study, we performed the QuantiFERON-Monitor test in 80 subjects including 54 patients with ESKD. QuantiFERON-Monitor is based on the measurement of plasma interferon-gamma (IFN-γ) after stimulation of NK-cells with a TLR-7 agonist, and T-cells with a TCR agonist. Patients were subsequently followed for 6 to 12 months. RESULTS: QuantiFERON-Monitor showed lower stimulated IFN-γ production in ESKD patients (n = 54) compared to healthy donors (n = 19) (p < 0.0001) and to chronic kidney disease stage 3-4 patients (n = 7) (hemodialysis (n = 30): p < 0.01; peritoneal dialysis (n = 13): p = 0.03 and ESKD on conservative management (n = 11): p < 0.001). No significant difference in stimulated IFN-γ production was observed between ESKD patients with renal replacement therapies or conservative management. Stimulated IFN-γ production was significantly lower in patients later developing infections (13.9 [5.5-48.3] IU/mL vs 85.8 [35.5-236] IU/mL, p = 0.007). Using ROC analysis, we identified a cutoff value of 63.55 IU/mL (sensitivity = 80.95%, specificity = 79.17%, AUC = 0.78, p = 0.008) to discriminate patients at higher risk of infections. Patients with stimulated IFN-γ levels measured by QuantiFERON Monitor below 63.55 IU/mL (n = 21) had a hazard ratio of 10.71 ([3.68-31.13], p < 0.0001) for the development of subsequent infections. CONCLUSION: Monitoring of IFN-γ production after stimulation of innate and adaptive immunity may identify ESKD patients with high risk of infection. This allows for therapeutic interventions to restore cellular immunity, thereby minimizing both infections and rejections after kidney-transplantation.

Breast milk immune complexes are potent inducers of oral tolerance in neonates and prevent asthma development.

Allergic asthma is a chronic lung disease resulting from an inappropriate T helper (Th)-2 response to environmental antigens. Early tolerance induction is an attractive approach for primary prevention of asthma. Here, we found that breastfeeding by antigen-sensitized mothers exposed to antigen aerosols during lactation induced a robust and long-lasting antigen-specific protection from asthma. Protection was more profound and persistent than the one induced by antigen-exposed non-sensitized mothers. Milk from antigen-exposed sensitized mothers contained antigen-immunoglobulin (Ig) G immune complexes that were transferred to the newborn through the neonatal Fc receptor resulting in the induction of antigen-specific FoxP3(+) CD25(+) regulatory T cells. The induction of oral tolerance by milk immune complexes did not require the presence of transforming growth factor-beta in milk in contrast to tolerance induced by milk-borne free antigen. Furthermore, neither the presence of IgA in milk nor the expression of the inhibitory FcgammaRIIb in the newborn was required for tolerance induction. This study provides new insights on the mechanisms of tolerance induction in neonates and highlights that IgG immune complexes found in breast milk are potent inducers of oral tolerance. These observations may pave the way for the identification of key factors for primary prevention of immune-mediated diseases such as asthma.