[Assessment of baseline CCL19+ dendritic cell infiltration for predicting responses to immunotherapy in lung adenocarcinoma patients].

Objective: To explore the correlation of baseline CCL19⁺ dendritic cell (CCL19⁺ DC) infiltration in lung adenocarcinoma microenvironment with immunotherapy efficacy and CD8⁺ T cell infiltration.

Methods: We retrospectively analyzed the data of patients with lung adenocarcinoma hospitalized at First Affiliated Hospital of Henan University of Science and Technology from January, 2020 to December, 2023, and collected tissue samples from 96 patients undergoing immunotherapy for assessing CCL19⁺ DC and CD8⁺ T cell infiltration using immunofluorescence assay. We evaluated the predictive value of baseline CCL19⁺ DCs for patient responses to immunotherapy using receiver-operating characteristics (ROC) curves and analyzed the correlations of baseline CCL19⁺ DC expression with immunotherapy efficacy and CD8⁺ T cell and cytotoxic T lymphocyte (CTL) infiltrations. In co-culture systems of lung adenocarcinoma PC9 cells, CD8⁺ T cells and DCs (overexpressing CCL19 with or without anti PD-1 antibody treatment), the expressions of granzyme B, perforin, IFN-γ, and Ki-67 in T cells were analyzed using flow cytometry.

Results: The patients with partial or complete remission following immunotherapy had a significantly higher baseline CCL19⁺ DC infiltration level in lung adenocarcinoma tissues than those with poor responses. CCL19⁺ DC infiltration had an area under ROC curve of 0.785, a sensitivity of 75.6%, and a specificity of 62.8% for predicting immunotherapy efficacy. The expression of CD8⁺ T cell surface molecules Granzyme B (P<0.01), Perforin (P<0.01), IFN-γ (P<0.01) and Ki-67 (P<0.001) in patients with high expression of CCL19⁺ DC were higher than those in patients with low expression of CCL19⁺ DC. The baseline CCL19⁺ DC infiltration level was positively correlated with immunotherapy efficacy (P=0.003), CTL infiltration of (r=0.6657, P<0.001) and CD8⁺ T cell infiltration (P=0.007). In the co-cultured cells, CCL19 overexpression combined with anti-PD1 treatment of the DCs more strongly enhanced cytotoxicity and proliferation of CD8⁺ T lymphocytes than either of the single treatments (P<0.01 or 0.001).

Conclusion: The baseline CCL19⁺ DC infiltration level in lung adenocarcinoma microenvironment is positively correlated with immunotherapy efficacy and CTL infiltration and can thus predict the response to immunotherapy.