Immune status of patients with community-acquired pneumonia associated with a new coronavirus infection and other viral and bacterial pathogens

Despite the fact that the state of the individual’s immune system plays an important role in developing community-acquired pneumonia, its clinical features are determined not only by immune response characteristics, but also by the nature of the infectious agent. The aim of the work was to assess immune status of patients with community-acquired pneumonia with lung damage ranging from 2 to 12%, in whom pathogens of a viral, bacterial and fungal nature were verified (n = 96, aged 46,3±20,5) who were admitted to the hospital 5–7 days after disease onset. Materials and methods. The selection of smears and sputum specimens was carried out on day 1 after admission. COVID-19 pathogen was analyzed in smears by PCR using the Vector-PCRR-2019-nCoV-RG kit (SSC Vector of Rospotrebnadzor, Russia). Biochemical activity, colony morphology, and pathogen concentration (in the amount of ≥ 10⁵ CFU/ml) were also evaluated. Based on the results of preliminary studies, target patients groups were formed: with a new coronavirus infection caused by the SARS-CoV-2 gene variant B.1.1.529 (Omicron) (n = 33); with COVID-19 and bacterial pathogens (n = 17); with COVID-19 and combined bacterial and fungal infection (n = 16); patients with identified pathogens of bacterial infections (n = 13); patients with combined bacterial and fungal infection (n = 17). The relative and absolute level of CD45⁺CD3⁺ lymphocytes, CD45⁺CD3⁺CD4⁺ cells, CD45⁺CD3⁺CD8⁺ lymphocytes, CD45⁺CD3-CD16⁺CD56⁺ cells, CD45⁺CD3⁺CD16⁺CD56⁺ lymphocytes, CD45⁺CD45RO^–CD45RA⁺ and CD45⁺CD45RO⁺CD45RA^– lymphocytes, CD45⁺CD19⁺ cells, CD45⁺CD5⁺CD19^–CD27^– and CD45⁺CD19⁺CD5^–CD27^– lymphocytes, CD45⁺CD19⁺CD5^–CD27⁺ cells was assessed in all volunteers. Results. The analysis of the immune status of patients with community-acquired pneumonia associated with Omicron gene variant new coronavirus infection revealed T-lymphocytopenia, a decreased number of CD8⁺ lymphocytes, an increased relative and absolute number of NK cells. In COVID-19 patients, who also had bacterial pathogens verified, there was a decrease in relative and absolute number of T-helper cells, an increased relative and absolute number of B and B2 lymphocytes. In COVID-19-negative volunteers with bacterial and bacterial-fungal community-acquired pneumonia, the relative and absolute level of B and B2 lymphocytes, as well as the general memory B cell population, was increased. In contrast to COVID-19-positive patients, in the absence of T-lymphocytopenia, a decreased number of CD4⁺ cells and rise in number of cytotoxic lymphocytes were recorded in patients of these groups. Conclusions. The data obtained indicate that in the immune status of patients with community-acquired pneumonia, depending on the nature of the infectious agent, changes in relative and absolute level of T-helper cells, cytotoxic lymphocytes, as well as in the qualitative and quantitative B-lymphocyte population composition are recorded.