In this phase, they migrate to the secondary lymphoid tissue and/or spleen, where they become transitional B-cells and can be dormant for several years. Subsequently, B-cell activation and maturation take place

once they encounter an antigenic stimulus and form a specific response. This specific response results in either isotype switching and antibody production, or presenting the foreign molecule to T cells Inhibitors,research,lifescience,medical via the major histocompatibility complex (MHC). As mature B-cells, they will express important molecules such as CD19, CD20, and CD22. Concomitantly, B-cells will interact with other components of the immune system (i.e., complement) to mount a specific immune reaction that will clear the system of the antigen. The B-cell interaction with several portions of the immune system represents an important natural defense mechanism. However, in the case of heart failure, it also can be a mediator of disease and disease severity when

Inhibitors,research,lifescience,medical self proteins are recognized as foreign and an immune response is mounted. More importantly, existing data demonstrates that the manipulation of B-cell maturation, activation, and interaction processes can cause major effects in the cardiovascular system. B-Cells and the Implications in Heart Failure A link exists between the different arms of the immune system, Inhibitors,research,lifescience,medical specifically B-cells, and heart failure. As shown by Nishimura et al., mice lacking programmed cell death protein-1 Inhibitors,research,lifescience,medical (PD-1-/-), a key factor for B-cell differentiation, develop a severe form of spontaneous dilated cardiomyopathy (DCM) and express high levels of circulating IgG that binds

specifically to cardiac myocytes.2 Furthermore, others have reported similar findings with the formation of antibodies against troponin I.3 However, this effect was not observed Inhibitors,research,lifescience,medical in PD-1-/- mice that also had defective T- and B-cells (RAG2-/-, Recombination Activation Gene). Similarly, unpublished data from our group demonstrates that SCID mice, which are T- and B-cell deficient due to a defective maturation process in V(D)J recombination, do not fully develop acute cardiomyopathy (CMP) in a nonischemic mouse model (Figure 1). This result is explained by the idea that absent or defective B-cells attenuate the expression of acute no CMP. Similarly, Xiu et al. demonstrated a delay in disease progression with the depletion of B-cells in Selleck PS 341 autoimmune illnesses, as in the case of autoimmune diabetes.4 These findings all support the idea that B-cells play a key role in immunity homeostasis, and alterations in B-cell expression can affect several systems, including the heart and its function. Figure 1. Absence of B- and T-cells prevents the development of fibrosis in a mouse model of acute cardiomyopathy.