Abstract
ABSTRACT Introduction: Studies suggest the association between antibody production and the severity of coronavirus disease 2019 (Covid-19). Objectives: To evaluate the concentrations of immunoglobulins class A (IgA) and class G (IgG) during the hospitalization period of Covid-19 patients according to the outcome (survival vs death). Materials and methods: Patients with severe acute respiratory syndrome of coronavirus 2 (Sars-CoV-2) infection confirmed by reverse transcriptase reaction followed by polymerase chain reaction (RT-PCR) were included in this prospective study. Samples were obtained weekly during the follow-up of individuals, considering symptom onset. Titers of anti-Sars-CoV-2 IgA and IgG were measured using a commercial immunoassay. Correlations between IgA/IgG and cycle threshold (Ct) values for N1 and N2 target genes were also assessed. Results: We studied 55 Covid-19 patients (59.7±16.2 years, 63.6% male), of which 28 (50.9%) died. We observed IgA and IgG positivity (IgA+ and IgG+) in 90.9% and 80% of patients, respectively. The highest IgA+ frequency was observed at weeks 2 and 3 and the highest IgG+ at weeks 3 and 4. It is important to note that patients who died presented lower IgA titers in the first two weeks (p < 0.05); however, a significant increase in IgA levels was observed in the subsequent weeks. Lastly, we identified that significant correlations between Ct values and immunoglobulins levels, both IgA and IgG were correlated with Ct N2 in patients who died. Conclusion: Our results suggest that lower IgA titers in early Covid-19, which is associated with lower Ct values, may indicate patients at higher risk for death.
Highlights
The history of muscle biopsy dates back to 1860, when Duchenne first performed a biopsy on a patient with symptoms of myopathy[1]
The twenty-first century has brought in a new spectacular progress in the utility of muscle biopsy with the commencement of molecular methods
The molecular era was made possible by the development of molecular biology and its application to muscle diseases
Summary
The history of muscle biopsy dates back to 1860, when Duchenne first performed a biopsy on a patient with symptoms of myopathy[1]. The introduction of enzyme histochemical methods by Victor Dubowitz, in 1970, revolutionized the role of muscle biopsy in the diagnosis of various primary and secondary muscle diseases[2]. The adaptation of histo- and cytochemical techniques to the study of muscle biopsies improved diagnostic accuracy and enabled the identification of new changes and structures[3, 4].
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