Clinical relevance of serum α-l-fucosidase activity in the SARS-CoV-2 infection.

BACKGROUND AND AIMS: The reduced fucosylation in the spike glycoprotein of SARS-CoV-2 and the IgG antibody has been observed in COVID-19. However, the clinical relevance of α-l-fucosidase, the enzyme for defucosylation has not been discovered. MATERIALS AND METHODS: 585 COVID-19 patients were included to analyze the correlations of α-l-fucosidase activity with the nucleic acid test, IgM/IgG, comorbidities, and disease progression. RESULTS: Among the COVID-19 patients, 5.75% were double-negative for nucleic acid and antibodies. All of them had increased α-l-fucosidase, while only one had abnormal serum amyloid A (SAA) and C-reactive protein (CRP). The abnormal rate of α-l-fucosidase was 81.82% before the presence of IgM, 100% in the presence of IgM, and 66.2% in the presence of IgG. 73.42% of patients with glucometabolic disorders had increased α-l-fucosidase activity and had the highest mortality of 6.33%. The increased α-l-fucosidase was observed in 55.8% of non-severe cases and 72.9% of severe cases, with an odds ratio of 2.118. The α-l-fucosidase mRNA was irrelevant to its serum activity. CONCLUSION: The change in α-l-fucosidase activity in COVID-19 preceded the IgM and SAA and showed a preferable relation with glucometabolic disorders, which may be conducive to virus invasion or invoke an immune response against SARS-CoV-2.

Differential diagnosis and prospective grading of COVID-19 at the early stage with simple hematological and biochemical variables.

We evaluated simple laboratory variables to discriminate COVID-19 from bacterial pneumonia or influenza and for the prospective grading of COVID-19. Multivariate logistic regression and receiver operating characteristic curve were used to estimate the diagnostic performance of the significant discriminating variables. A comparative analysis was performed with different severity. The leukocytosis (P = 0.017) and eosinopenia (P = 0.001) were discriminating variables between COVID-19 and bacterial pneumonia with area under the curve (AUC) of 0.778 and 0.825. Monocytosis (P = 0.003), the decreased lymphocyte-to-monocyte ratio (P < 0.001), and the increased neutrophil-to-lymphocyte ratio (NLR) (P = 0.028) were predictive of influenza with AUC of 0.723, 0.895, and 0.783, respectively. Serum amyloid protein, lactate dehydrogenase, CD3+ cells, and the fibrinogen degradation products had a good correlation with the severity of COVID-19 graded by age (≥50) and NLR (≥3.13). Simple laboratory variables are helpful for rapid diagnosis on admission and hierarchical management of COVID-19 patients.