Pathomorphological and immunohistochemical features of lymph nodes in COVID-19 patients (autopsy study)

Abstract

Introduction. The pathogenesis of the novel coronavirus infection COVID-19 is being actively studied. Nevertheless, our up-to-date knowledge of lymphoid tissue response in the secondary immune organs dur-ing severe COVID-19 remains extremely limited. The aim of the study was to evaluate patterns of immu-nomorphological alterations in lymph nodes in patients with severe COVID-19 and to assess lymphocytes functional activity in them. Materials and methods. Lymph node tissue (autopsy material) from 17 deceased patients with severe COVID-19 was examined by histological and immunohistochemical methods using antibodies to CD4, CD8, CD20, CD30, CD123, CD138, PD-1. Results. Examined lymph nodes demonstrated lymphoid follicles reduction and paracortex expansion with reactive plasmacytosis and extrafollicular B-cell activation as well as sinus histiocytosis, variable hemophago-cytic cells, and blood vessel congestion. Red thrombi were observed in some lymph nodes. Hemorrhages in the stroma were frequent, and massive hemorrhages were found in individual nodes. Immunohistochemical study revealed CD4+ T-helpers predominance in the paracortex andcytotoxic CD8+ lymphocytes depletion together with an increase in the expression of both the PD-1 suppressor protein and the CD30 activation anti-gen on the lymphocyte surface. CD123-positive plasmacytoid dendritic cells resided in sinuses in abundance. Conclusion. Demonstrated B-associated zone reduction and cytotoxic T-lymphocytes depletion with an up-regulation of PD-1 expression in the lymph nodes in patients with severe COVID-19 indicate immune response exhaustion. At the same time, observed significant reactive plasmacytosis with the presence of numerous T-helper cells constitutes a morphological substrate of the humoral immunity. These findings might indicate the ineffec-tiveness of the humoral response at late stages of COVID-19 infection in context of cytotoxic immunity failure. Keywords: novel coronavirus infection, SARS-CoV-2, COVID-19, B- and T- immune response, lymph node

Pathological Features in 100 Deceased Patients With COVID-19 in Correlation With Clinical and Laboratory Data

“…Tubular necrosis and renal infarctions, associated with septic conditions, were seen in 2 cases in our study. Splenic enlargement due to sepsis, major follicular reduction, lymphatic infiltration, necrosis and [45]. The paracortical zone showed a significant reactive plasmocytosis with T-helper existence-a morphologic substrate of humoral immunity, which may testify a noneffective humoral response in COVID-19-effected patients with simultaneous T-cell immunity failure.…”

“…An immunohistochemical study revealed the predominance of CD4 + T-helpers in the paracortical zone, depletion of cytotoxic CD8 + lymphocytes, an increase in the number of both lymphocytes expressing the PD-1 suppressor protein and activated lymphocytes expressing the CD30 activation antigen. CD123-positive plasmacytoid dendritic cells secreting type 1 interferon were found in a significant amount in the lumen of the sinuses and in the paracortical zone [45].…”

Pathomorphological Features of the Novel Coronavirus Disease in Patients with Systemic Amyloidosis

“…Cardiac complications caused by infection with SARS-CoV-2 are deemed to be associated with both direct and indirect viral effects on the myocardium. The direct mechanism of myocardial injury is promoted by a viral invasion of cardiomyocytes via the viral S-protein, a type of transmembrane glycoprotein, and the interaction of the virus with angiotensinconverting enzyme (ACE) 2 present in cardiac cells [41][42][43]. However, the viral entry into cardiomyocytes depends not only on the viral S protein binding to the host-cell receptors.…”