Programmed cell death receptor 1 (PD-1) is one of the major immune checkpoints. Due to the lack of reports on PD-1- and PD-L1-positive lymphocyte proportions in patients with recurrent furunculosis, we aimed to evaluate percentages of those cells in the peripheral blood and to assess their correlations with other lymphocyte subsets, and the level of cell activation measured by the expression of CD25 and CD69 molecules on T lymphocytes. We recruited 30 patients with recurrent furunculosis and 15 controls. The amount of 5 mL of peripheral blood was collected for laboratory tests. Patients with chronic furunculosis presented with the similar number of lymphocytes, CD4+ T lymphocytes, CD8+CD3+ T suppressor lymphocytes, and CD19 + B lymphocytes to controls, but significant differences were found between subpopulation of those cells. Furunculosis patients had the significantly elevated percentage of lymphocytes with PD-1 and PD-L1 on their surface. Early onset of furunculosis was correlated with a higher percentage of CD19 + PD1 B lymphocytes. Greater number of skin lesions correlated with a decrease in the CD4PDL1+ cells, which subsequently was associated with an increase in the percentage of Treg cells, NKT cells, CD8+CD3+ lymphocytes and B lymphocytes. Changes in the proportion of immune cells may lead to reduced inflammatory reactions in patients with recurrent furunculosis. In the light of mechanisms of S. aureus invasion, the degree of immune impairments in the scope of adaptive immunity seems to play a significant role in the course of furunculosis. PD-1 and PD-L1 molecules change the host response and affect the ongoing inflammatory process.
Keywords: PD-1; Recurrent furunculosis; Staphylococcus aureus.
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