Activity of Negative Regulation of the PD-1/PD-L1/PD-L2 T-Cell Response System in Patients with Pneumonia and Influenza A (H1N1)

Systemic inammation is an integral pathophysiological component of many critical illnesses. The systemic inammatory response is based on a cascade of interactions leading to hypercytokinemia and, as a consequence, multiple organ failure, which is one of the main causes of mortality in intensive care units. Aim of the study . To evaluate the activity of the negative regulation system of T-cell response by determining the plasma levels of PD-1, PD-L1 and PD-L2 molecules in pneumonia patients with inuenza A (H1N1). Materials and methods . 85 patients with pneumonia and underlying inuenza A (H1N1) were examined. Among them there were 30 patients with severe pneumonia, and 55 patients with non-severe pneumonia. Plasma levels of PD-1, PD-L1, PD-L2 molecules was determined by ow cytouorometry method. Results . In patients with severe pneumonia and underlying inuenza A (H1N1), the plasma level of PD-1 receptor increased 4.6-fold, while the concentration of its ligands PD-L1 and PD-L2 increased 10.6 and 2.2-fold, respectively. Conclusion . Signicant increase in levels of PD-1 and its ligands PD-L1 and PD-L2 in patients with pneumonia and underlying inuenza A (H1N1) indicates the involvement of negative regulation system of T-cell response in the cascade of immunological reactions and is associated with the severe disease. Possible correction of immune reactions realized through PD-1/PD-L1/PD-L2 complex in critically ill patients is a promising research avenue.