Immunological Characteristics of Chronic Brucellosis and Preliminary Study on CD8 Tem for Efficacy Evaluation

Objective This study aimed to elucidate the immunological characteristics of chronic brucellosis and to screen for objective indicators for monitoring treatment efficacy.Methods An integrated analysis of transcriptomic data from the GEO database was performed to identify differentially expressed genes between chronic brucellosis patients and healthy controls. Single-cell RNA sequencing (scRNA-seq) combined with flow cytometry was utilized to profile the immune cell atlas of peripheral blood mononuclear cells from patients in the chronic and recovery phases.Results Compared to healthy controls, chronic-phase patients exhibited a significant increase in CD8⁺ T cells. At the single-cell level, 11 immune cell subsets were identified. Among these, CD8 Tem cells were significantly decreased in recovery-phase patients compared to those in the chronic phase. Six candidate genes were screened and shown to have potential for evaluating treatment efficacy in chronic brucellosis patients. Flow cytometry validation confirmed the significant decrease in CD8 Tem cells in recovery-phase patients compared to chronic-phase patients.Conclusion A deep understanding of the differences in the immune microenvironment is crucial for better screening of efficacy evaluation indicators for chronic brucellosis patients. CD8 Tem cells may serve as a potential biological marker for assessing the therapeutic effect of chronic brucellosis.