Abstract
Programmed death-1 (PD-1) is one of the most important inhibitory co-receptors expressed predominantly on activated T and B lymphocytes whose expression could be sustained by permanent antigenic stimulation accompanying chronic or recurrent tonsillitis. The expression of PD-1 and PD-1L was analyzed using flow cytometry on hypertrophied tonsils collected from 57 children. We observed high expression of PD-1 and PD-1L on certain lymphocytes subpopulations of hypertrophied tonsils; among T cells, the expression of PD-1 on protein level was higher on CD4+ cells (70.3 %) than on CD8+ cells (35 %). Interestingly, a limited expression of PD-1 was observed on CD19+ B lymphocytes (6.5 %), while CD5+CD19+ B cells overexpressed PD-1 (52.5 %). Moreover, the expression of PD-1L was also higher on CD5+CD19+ B cells (16.5 %) than on CD19+ B cells (3.5 %) and on CD4+ T cells (20 %) than on CD8+ T cells (10 %). PD-1 and PD-1L expressions correlated only on CD5+CD19+ cells. In conclusion, high expression of PD-1 and PD-1L on T and B cells could represent hallmark of immune system adaptation to chronic antigenic exposition in patients with tonsillitis.
Highlights
Recurrent viral and bacterial infections are the major underlying causes of tonsillitis, which typically is a selflimiting localized inflammation of the oropharynx
The main purpose of this work was to characterize the expression of programmed death-1 (PD-1) and programmed death-1 ligand (PD-1L) on certain lymphocytes subpopulations of hypertrophied tonsils obtained by tonsillectomy from children with recurrent exacerbations of
We found the median frequency of CD4? T lymphocytes of 14.5 % and the median frequency of CD8? T lymphocytes of 5.5 % in tonsillar tissue
Summary
Recurrent viral and bacterial infections are the major underlying causes of tonsillitis, which typically is a selflimiting localized inflammation of the oropharynx. These infections upon continuous antigenic stimulation could induce histomorphological and functional changes in the tonsils, making tonsillectomy necessary [1]. In subepithelial area of tonsils, B1 lymphocytes represent about 15 % of B cells. The main role of B1a lymphocytes is to produce ‘‘natural,’’ low-affinity and polyreactive IgM which could bind different bacterial antigens and autoantigens representing a bridge between innate and adaptive immune responses [3, 4]
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