Analysis of peripheral lymphocyte subsets and T-cell exhaustion in SARS-CoV-2 Infection.

Introduction: : Immune responses against Coronavirus (SARS-CoV-2) may be highly complex. It has been suggested that T-cell fatigue develops due to continuous stimulation of T-cells by SARS-CoV-2 in Coronavirus disease-2019 (COVID-19). It was aimed to assess peripheral lymphocyte subsets and T-cell exhaustion in various clinical courses of the disease in patients diagnosed with COVID-19. Materials and Methods: This study included 150 patients who were assigned into the "mild-to-moderate disease" group, or "severe disease" group based on their clinical and laboratory characteristics. Peripheral lymphocyte subsets and T-cell exhaustion markers [programmed cell death protein 1 (PD-1) and T-cell immunoglobulin and mucin-domain containing-3 (Tim-3)] were determined in the peripheral blood using flow cytometry. Result: Mean (±SD) age was 53.3 ± 14.5 years, and female to male ratio was 55/95. In the mild-to-moderate disease (MMD) group, 55 patients had pneumonia and 20 patients had COVID-19 without pneumonia. In the severe disease (SD) group, 43 patients had severe pneumoniae and 32 patients were in critical condition. Lymphocyte counts were less than 1.0 x 109/L in 69.3% of the patients in the SD group, and the difference between the MMD group and SD group was statistically significant (p= 0.001). Total T cells, CD4+ and CD8+ T-cell counts were significantly lower in the SD group vs. MMD group (p< 0.001, p< 0.001, p< 0.001, respectively). PD-1 expression by CD8+ and CD4 T+ cells was higher (p= 0.042, p= 0.029, respectively) and Tim-3 expression from CD4 T+ cells was lower (p= 0.000) in the SD group vs. MMD group. Serum IFN-γ levels were not statistically different in the MMD and SD groups (p= 0.2). Conclusions: T-cell counts may be significantly reduced along with an increased expression of the T-cell exhaustion marker PD-1 in severe COVID-19, but Tim-3 expression was not increased in our study patients.

Risks and prediction of postoperative hypoparathyroidism due to thyroid surgery.

We aimed to investigate the prevalence of postoperative hypoparathyroidism (PoH), the relevant factors, and predictors of transient or permanent hypoparathyroidism. The files of 352 patients who underwent bilateral total thyroidectomy alone or with central lymph node dissection and/or lateral neck dissection between June 1, 2019, and November 30, 2019, were retrospectively evaluated. Also, calcium and parathyroid hormone levels measured preoperatively and 4-6 h after surgery, follow-up examination results, and time to resolution of transient PoH were recorded. 16.48% (n = 58) of the surgical patients developed transient PoH and 3.98% (n = 14) developed permanent PoH. Length of hospital stay increased in patients who developed PoH (p < 0.001). Transient PoH developed less in patients who underwent parathyroid autotransplantation, while permanent PoH was not detected (p = 0.001). PoH development was not significantly correlated with nodule size as measured by preoperative thyroid ultrasonography (p = 0.944). Patients who had a serum PTH level ≤ 5.95 pmol/L 4-6 h after surgery had a greater risk of developing permanent PoH (OR 134.84, 95% CI 17.25-1053.82). PoH is more common in female gender and is not significantly correlated with nodule size. Parathyroid autotransplantation can prevent the development of PoH.