Tumor PD-L1 overexpression leads to suppression of cytotoxic adaptive immunity. Recently high level of Interleukin-1 beta (IL-1β) in the tumor microenvironment (TME) was reported to be associated with immunosuppression of lymphocytes. The ratio of neutrophils and lymphocytes (NLR) in the tumor tissue and in the peripheral blood reflects the activity of adaptive immunity. The aim of this work is to study the relationship between the tumor expression of the PD-L1, the concentration of serum IL-1β, a possible marker of TME activity, and NLR, a marker of adaptive immunity activity.
The serum samples of patients with various solid tumors (n=48) before the start of checkpoint inhibitors therapy were collected. The serum level of IL-1-β was measured with ELISA (\"ELISA-best\", Novosibirsk, Russia), tumor PD-L1 expression was determined by immunohistochemical method, a full blood count by cytometry. The results obtained were analyzed in GraphPad Prism 6 (Graph Pad Software, USA) using Fisher, Mann-Whitney, and Spearman's statistical analysis. The project is supported by grant (contract №20-015-00498/20).
Positive PD-L1 expression was observed in 72,92% (35/48) of the patients, while IL-1β was detected in 66,67% (32/48) and high NLR was registered in 35,42% (17/48). The tumor PD-L1 expression had a positive statistically significant low correlation with serum IL-1β concentration (r=0,327; p=0,037) and the NLR (r=0,327; p = 0,034). IL-1β level was positively correlated with NLR (r= 0,353; p= 0,025). In a group with positive PD-L1 expression the mean concentration of IL-1β was 1,65± 0,54 pg/ml, the mean NLR was 4,26±0,94 109/L, what exceeds the meanings of the group with negative expression, but without statistical significance.
The study revealed a positive correlation between the tumor PD-L1 expression, the serum IL-1β concentration and the NLR. The obtained result may indicate the influence of the immunosuppressive properties of the tumor on the state of the patient's immunity. A comprehensive determination of tumor PD-L1 expression, serum IL-1β concentration and NLR can be used as an assessment of the patient's immune status before starting treatment with checkpoint inhibitors.
Legal entity responsible for the study
Russian Foundation for Basic Research (RFBR) - Project number 20-015-0049820 of 19.02.2020.
All authors have declared no conflicts of interest.