In-utero exposure to these autoantibodies due to placental crossing can also

result in permanent impairment to fetal development. These high-risk pregnancy conditions often result in poor outcomes such as preterm birth and low birth weight that also increase significantly the predisposition of a newborn to developmental disability and chronic Depsipeptide diseases later in life [7-10]. B cell depletion therapy has proven clinical benefits in the management of autoimmune conditions outside pregnancy. In this review, we will examine the available evidence of the possible contribution of B cells in shaping pregnancy outcomes and discuss the implication of B cell depletion in the clinical management of high-risk pregnancy. B cells, while known primarily for antibody production, also act as antigen-presenting cells and regulators of the LEE011 molecular weight innate and adaptive immune systems [4, 5]. The murine B cell compartment consists of two general populations, namely B1 and B2 cells. These cells have major differences in their phenotypes, anatomical location and functional characteristics [11,

12]. In humans, the existence of a human B1 subset is still a contentious subject, and the distinctions between B1 and B2 cells remain undefined [12]. Nevertheless, both murine B1 and human B1-like cells have been characterized as B cell subsets that spontaneously secret large amounts of polyreactive natural antibody IgM against double-stranded DNA (dsDNA), phosphorylcholine (PC) and low-density lipoproteins [11-14]. In the mouse, B1 cells have been characterized by a pattern of surface markers of B220low, immunoglobulin (Ig)Mhi, IgDlow, CD5+/–, CD43+ and CD23– expression, whereas B2 cells generally express B220hi, IgMhi/lo, IgDhi, CD43– and CD23+ markers but not CD5 markers, although B2 cells have been shown

to express low levels of CD5 following activation in vitro and in some studies GSK-3 inhibitor CD5 expression has been shown on anergic B2 cells [12, 13]. In humans, CD5 expression has been described on both B1-like and activated B2 cells [12]. Recently, it has been suggested that the human B1-like cell population may include the circulating CD5+/–CD20+CD27+CD43+IgM+IgD+ B cell subset [14]. However, the definitive markers for the general human B1 cell population remain to be determined. B2 cells are known as conventional B cells, which make up the majority of the splenic B cell population. Unlike B1 cells, which appear in fetal liver tissue as early as mid-gestation and are regenerated by self-renewal processes in the peritoneal cavity, B2 cells emerge from bone marrow stem cells during the late neonatal period and their clones are selected by a stringent process of clonal deletion and expansion in the germinal centre of the spleen [12, 13].