Plasma Cells

Although the overproduction of immunoglobulins by short-lived plasma cells accompanying an immune response links with their apoptosis, how long-lived plasma cells adapt to ensure their longevity in this context is obscure. Here, we show that apoptosis signal-regulating kinase 1 (ASK1) contributes to apoptosis of plasma cells because ASK1 activity was induced during differentiation of short-lived plasma cells, and, when produced by ASK1-deficient mice, these cells survived better than those of control mice.

Antibodies continuously secreted by plasma cells play a central role in humoral immune protection of the organism. These plasma cells are generated during the germinal center reaction, and it is likely that they here acquire the potential to develop into long-lived cells. To achieve longevity, these cells require factors provided by the microenvironment. Indeed, only a few of the plasmablasts arising during an immune response will differentiate into mature plasma cells, which may survive for decades in specialized survival niches in the bone marrow.

Antibody production is an important feature of the vertebrate immune system. Antibodies neutralize and clear pathogens, thereby protecting against infectious diseases. Such humoral immunity has great longevity, often persisting for the host's lifetime. Long-lived humoral immunity depends on help provided by CD4(+) T cells, namely T follicular helper (TFH) cells, which support the differentiation of antigen-specific B cells into memory and plasma cells.

It is well accepted that Ag-induced B cell differentiation often results in the generation of exceptionally long-lived plasma cells. Much of the work supporting this viewpoint stems from studies focused on germinal center-derived plasma cells secreting high-affinity isotype-switched Abs in mice immunized with T cell-dependent Ags. In contrast, less attention has been devoted to understanding Ab responses to T cell-independent Ags and pathogens.

Alloantibody can be a major barrier to successful organ transplantation; however, therapy to control antibody production or to alter its impact on the allograft remains limited. The goal of this review is to examine the regulatory steps that are involved in the generation of alloreactive B cells, with a specific emphasis on how known mechanisms relate to clinical situations in transplant recipients. Thus, we will examine the process of activation of mature, naÔve B cells and how this relates to de novo antibody production.

We have previously shown that immunization with SIV-, SHIV-, or HA (influenza hemagglutinin)-virus-like particles (VLPs) elicits a strong humoral immune response in mice. However, little is known about the action VLPs exert on immune effector cells, including B cells. In this study, we found that all three types of VLPs could directly bind and activate B cells in vitro. VLPs stimulated the proliferation of B220(+)IgM(+)CD43(-)CD5(-) B2 cells and their differentiation to plasma cells that preferentially produce IgG2a antibodies.

Chronic sialectatic parotitis (CSP) causes problems in differential diagnosis and therapy. CSP shows the typical clinical features of chronic recurrent parotitis and will be investigated histopathologically only after ultimative parotidectomy. The etiology and pathogenesis of these unspecific inflammations is still unknown. Therefore no causal therapy is available and a lot of different trials (sialogoga, gland massage, infrared light, antibiotics, antiphlogistics, Trasylol, duct occlusion, duct ligation, gland denervation, radiotherapy) are not successful in the long run.