High Frequency of IL10 Producing Regulatory B Cells (CD19+IL10+) As a Potential Biomarker of Leprosy Contact Monitoring

Background: Leprosy is a chronic infectious disease, caused by M. leprae which transmission is still persistent, nowadays. To reduce transmission it is essential early diagnose to identify infected individuals lacking clinical symptoms. In this context, it is noteworthy to look for immunological biomarkers applicable as complementary diagnostic tools to follow-up leprosy contacts. Regulatory B cells (Bregs) are known to exhibit their regulatory functions through interleukin-10 (IL-10). There are few studies of these cells in host immunity in leprosy. Our objective was to evaluate the role of Bregs in the pathogenesis of leprosy and their applicability as a biomarker.Methods: The study comprised a cross-sectional investigation that enrolled 16 participants, including 01 leprosy patient and 15 healthy contacts. Heparinized whole blood samples were collected from the patient before/ 5 days after treatment, from healthy contacts, and used to surface (CD19+) and intracytoplasmic cytokine (IL-10) staining of lymphocytes upon short-term in vitro culture.Results: We evaluated the frequency of Breg cells index (CD19+IL10+) and the total B cell index (CD19+), in an MB leprosy patient and his contacts. Notably, our strategy allows identifying household and social contacts with a profile of the total B cell (CD19+) and regulatory B cell (CD19+IL10+) index similar to the patient before treatment, suggesting that they could be latently infected with M. leprae.Conclusions: This approach showed that it is possible to use the Breg cells index as a biomarker for monitoring contacts, and understanding the involvement of B cells in the pathogenesis of leprosy.