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Background: Although there are a growing number of studies on evaluating lymphocyte subset counts as prognostic factors for COVID-19 disease severity, the lymphocyte subsets' analyses of both IgM and IgG responders and non-responders during the periods after onset of symptoms, have not been conducted yet. So, this study aimed to evaluate immune cell profiling of COVID-19 patients with and without antibody responses.Methods: In this cross-sectional study, the levels of peripheral lymphocyte subsets were measured using flow cytometry in 53 patients with positive SARS-CoV-2 RT-PCR, for whom antibody testing of COVID-19 was performed.Results: The white blood cell, neutrophil, and lymphocyte counts consistently decreased in the IgM and IgG non-responder group, while the differences in the median value between the two study groups were found to be statistically significant only in terms of neutrophil counts (P = 0.024 for IgM response and p-value = 0.046 for IgG response, respectively). Moreover, the level of neutrophil-to-lymphocyte ratio was observed to be significantly lower in the IgM or IgG non-responder group compared to the IgM or IgG responder group (3.6 ± 3.1 vs. 6.3 ± 4.2; p-value = 0.021). The patients with IgM antibody response had a significantly lower CD20+ lymphocytes (11% versus 15% in the groups without IgM antibody response, p-value = 0.031), The percentages of NK cells and CD4+ T cells significantly increased in the patients with IgG antibody response compared to those without IgG antibody response (13% versus 10%, p-value = 0.028, and 41.5% versus 34%; p-value = 0.03, respectively). Moreover, the patients who produced IgM or IgG antibody had significantly higher percentages of total T lymphocytes (64% versus 54%; p-value = 0.017), CD4+ T cells (41% versus 34%; p-value = 0.038), and NK cells (13% versus 9%, p-value = 0.023) compared to the group with no serological response. No significant difference was observed in the percentage of other lymphocyte subsets, including CD8+ T cells, Treg cells, and CD19+ B cells.Conclusion: Our results suggest that the total T cells, CD4+ T cells, and NK cells percentages are linked to serological response. Moreover, our findings suggested that neutrophil absolute counts and neutrophil-to-lymphocyte ratio may be valuable predictors of IgM or IgG antibody response. [ABSTRACT FROM AUTHOR]

BACKGROUND: There are few studies to compare antibody response against anti-spike (S) and anti- nucleoprotein (N) SARS-CoV-2. OBJECTIVE: The aim of this study was to evaluate the IgG antibody production against S and N antigens of the virus and their correlation with the time and severity of the disease. METHODS: The IgG antibodies against S and N antigens of SARS-CoV-2 in serum specimens of 72 symptomatic patients who tested real-time reverse transcription polymerase chain reaction positive for SARS-CoV-2 were detected using the ELISA technique. Different antibody response was compared and the correlation with the time from disease onset and the severity was evaluated. RESULTS: Forty-eight of 72 (67%) patients tested positive for anti-SARS-CoV-2 antibodies, while 24 (33%) did not have detectable antibodies. Comparison of antibody levels for N and S antibodies showed that they correlate with each other well (r = 0.81; P < 0.001). However, sensitivity of anti-S SARS-CoV-2 IgG and anti-N SARS-CoV-2 IgG was 30% and 60%, during the first 7 days after symptom onset (r = 0.53; P = 0.111), but increased to 73% and 68% at more than 1-week post symptom onset (r = 0.89, P = 0.111), respectively. Cases with positive IgG response showed a decreased CD8 + T cells percentage compared to the negative IgG groups (26 ± 14 vs. 58 ± 32, p = 0.066 in anti-N IgG group and 28 ± 15 vs. 60 ± 45, p = 0.004 in anti-S IgG group, respectively). CONCLUSION: Nearly one-third of the confirmed COVID-19 patients had negative serology results. Lower percent positivity at early time points after symptom onset (less than 1 week) was seen using anti-S SARS-COV-2 IgG kit compare to the anti-N SARS-CoV-2 IgG; therefore, clinicians should interpret negative serology results of especially anti-S SARS-CoV-2 IgG with caution. [ABSTRACT FROM AUTHOR]