Effects of osteopontin on B cells (P6285)

Abstract

Abstract Osteopontin (OPN) is a protein responsible for diverse processes. OPN expression is linked to autoimmunity and cancer. Both innate and adaptive immune cells like macrophages, dendritic cells,T and B cells express OPN. OPN has many effects on non-B immune cells, the source of these effects is either the OPN produced by the cells themselves or OPN made by other cells. With regard to B cells, it’s been suggested that high levels of OPN contribute to chronic and sustained polyclonal B cell activation. However, the specific effects of OPN on B cell survival, migration and stimulated proliferation are unknown. Our objective is to identify these specific effects of OPN on B cells and determine the contribution to disease activity. For survival studies, purified B cells from WT mice-untreated and treated with exogenous OPN were used along with B cells from OPN transgenic mice. Increased survival was seen in both OPN treated B cells and B cells from transgenic mice. Thymidine incorporation and CFSE assays were used to examine proliferation of B cells from WT and OPN transgenic mice in response to various stimuli. The results indicate enhanced proliferation in B cells from the transgenic mice compared to those from WT mice. Using transwell migration assay, preliminary experiments also indicate that OPN induces migration of B cells. These developments suggest that OPN affects B cell survival, proliferation and migration, which could in turn contribute to propagation of disease activity.