Abstract

Bowdichia virgilioides Kunth (Fabaceae) is a tree species used in folk medicine against inflammatory disorders, and it is still unclear whether consumption of the B. virgilioides stem bark extract has any effect on immune cells. Thus, this study aimed to evaluate the effects of B. virgilioides stem bark extract (AEBv) on the functions of the thymus and B lymphocytes. The AEBv was obtained by decoction and administrated orally once a day in male mice for 7 days. After treatment, thymi were obtained for morphology analysis, relative weight, cellularity and deposition of laminin. Thymocytes obtained from control and treated animals were submitted to adhesion and migration assays followed by immunophenotyping. Also, mesenteric lymph nodes were removed, and the lymphoid cells were obtained to measure B cell proliferation and cytokine production. Mice treated with AEBv and their controls were also immunized with sheep red blood cells (SRBC), and 8 days post immunization the sera were collected to perform antibody titration using hemagglutination assays. AEBv administration decreased thymus weight and cellularity and increased the laminin deposition without any significant effect on the expression of the laminin receptor VLA-6 in the thymus microenvironment. Additionally, thymocytes of AEBv-treated mice showed reduced adhesion and migration on laminin substrates, and the B lymphocytes showed reduced proliferation, enhanced IL-10 secretion, decreased TNF-α production, and attenuated anti-SRBC antibody production. These findings showed that AEBv intake might cause modulatory effects on the functions of thymocytes and B-lymphocytes, contributing to the treatment of immune diseases.

Key words: Thymocytes, cell migration, cell adhesion, immunosuppression, B cell.