Mucosal B cells and their function
Phillip D. Smith, Richard S. Blumberg, Thomas T. MacDonald in Principles of Mucosal Immunology, 2020
The structure of GALT is similar throughout the gastrointestinal tract with prominent B-cell follicles with intervening T-cell zones. CD4+ T cells in the outermost zone intermingle and interact with antigen-exposed B cells. GALT contains a marginal zone that resembles the splenic marginal zone and is surrounded by and merged with the memory B-cell population (Figure 10.1). Splenic and GALT marginal zone B cells are similar morphologically and are medium-sized cells with cleaved nuclei. These B cells are CD27+IgM+ and do not express high levels of IgD. Splenic marginal zone B cells have mutations in their IgHV genes that are acquired in the germinal centers of GALT. The GALT marginal zone also contains B cells with mutations in IgHV. Internal to and overlapping with the marginal zone is the mantle zone of IgD high naive B cells. The broadest aspect of the often narrow, crescent-shaped mantle zone faces the antigen-exposed FAE. Memory B cells expressing predominantly IgA or IgM (but not IgD) are located on the periphery of the B-cell area of GALT. At the center of the follicle is the germinal center. B cells proliferate and mutate in the cell-dense dark zone of the germinal center and are selected for further antigen-driven mutation and maturation by T-follicular-helper (TFH) cells in the light zone.
Embryology of the Spinal Cord, Peripheral Nerves, and Vertebrae
Bernard J. Dalens, Jean-Pierre Monnet, Yves Harmand in Pediatric Regional Anesthesia, 2019
At this stage, the meninges develop from the paraxial mesoderm, and three fundamental zones may be identified within the neural tube (Figure 1.10): The ependymal zone, next to the central canalThe mantle zone, outside the ependymal zone, in which neuroblasts and neuroglia can be identifiedThe marginal zone, formed mainly by growing nerve fibers (cells are scarce)
Pathology of the Spleen
Harold R. Schumacher, William A. Rock, Sanford A. Stass in Handbook of Hematologic Pathology, 2019
Mantle cell lymphoma (MCL) (mantle zone, centrocytic lymphoma, intermediately differentiated lymphocytic lymphoma) is a disease of older adults who often present with generalized lymphadenopathy. Splenomegaly is common and systemic involvement is seen at presentation in a quarter of the cases. Histologically, the mantle cell lymphocytes show a nodular monotonous effacement of white pulp, and cytologically they show round to irregular and slightly indented nuclear contours and scant cytoplasm. Immunophenotype findings are also characteristic (Table 4). Cytogenetically, a t(11;14)(q13;32) translocation corresponding to overexpression of bcl-1 oncogene is present in about half to two-thirds of cases.
Simultaneous presentation of orbital mantle cell lymphoma and endocrine mucin-producing sweat gland carcinoma
Published in Orbit, 2022
Darsh S. Shah, Natalie A. Homer, Aliza Epstein, Vikram D. Durairaj
Mantle-cell lymphoma (MCL) constitutes a rare and aggressive form of non-Hodgkin’s lymphoma that originates in the peripheral B-cells of the inner mantle zone of the lymph node. It is generally a disease of older individuals with a higher incidence in males.1 MCL is often associated with a t(11;14)(q13;q32) chromosomal translocation, which results in the upregulation of proto-oncogene B and its protein product Cyclin D-1.9,10 The most commonly affected sites of ocular adnexal involvement are the orbit (71%) and eyelids (64%).11 Clinically, patients who have an MCL in the ocular adnexa may present with proptosis, diplopia, conjunctival injection and irritation, or ptosis.12 Confirmatory immunohistochemical markers of ocular and nodal MCL include positive staining for B-cell-associated antigens CD20, CD22, CD29, and the T-cell-associated antigen CD5, with the absence of CD23, CD10, and BCL-6 expression.13 Additionally, Cyclin D-1 is expressed in 80–90% of MCLs and is typically absent in other B-cell lymphomas, including MALT-type orbital lymphoma. Morphologically, MCL is composed of small-to-medium-sized lymphocytes with irregularly shaped nuclei and minute or absent nucleoli.14 The morphological characteristics and immunohistochemical markers of our patient’s orbital lesion are consistent with those classically seen in MCL.
B cell maturation antigen (BCMA)-based immunotherapy for multiple myeloma
Published in Expert Opinion on Biological Therapy, 2019
Yu-Tzu Tai, Kenneth C Anderson
BCMA, a transmembrane glycoprotein [16] and non-tyrosine kinase receptor [17], belongs to the tumor necrosis factor receptor (TNFR) superfamily and is almost exclusively expressed in plasmablasts [18] and PCs [19,20]. In nonmalignant lymphoid tissue, BCMA protein is detected in the interfollicular area of germinal centers, but not in the follicular mantle zone [20]. Unlike the other two functionally related TNFRs B-cell activation factor receptor (BAFF-R) and transmembrane activator and calcium modulator and cyclophilin ligand interactor (TACI), BCMA is uniquely induced in late memory B cells committed to PC differentiation and is present in all PCs. In contrast, other normal tissues have undetectable BCMA transcripts except for plasmacytoid dendritic cells (pDCs) which express significantly lower BCMA levels than PCs from the same individuals [13,21]. Multiple independent studies using tissue gene expression profiling and immunohistochemistry as well as flow cytometry analysis indicate that BCMA [22] transcript and protein are strongly expressed in PCs and only weakly detected in normal organs due to PCs [12,13,15]. BCMA-/- mice have impaired long-term PC survival but show no defects in short-term production of immunoglobulins, early humoral immune response, and B-cell development [19,23]. Thus, BCMA is critical for differentiation and optimal survival of long-lived PCs in the BM but is dispensable for B cell homeostasis.
Considering the spleen in sickle cell disease
Published in Expert Review of Hematology, 2019
Sara El Hoss, Valentine Brousse
The white pulp of the human spleen consists of B lymphocytes found in the follicles and T lymphocytes mainly organized in sheaths surrounding arteries. B follicles are composed of a germinal center (GC) surrounded by a mantle zone. The GC consists of mainly B-cells and of T-cells in the periphery, very much like a lymph node structure [8]. This compartment of the spleen is responsible for the recirculation and clearing of lymphocytes, and importantly, initiating an immune response for blood-borne antigens. In particular, the follicular B-cells initiate a T-cell dependent immune response, while IgM memory B-cells lining the mantle zone in the spleen initiate a T-cell independent response, critical for the phagocytosis of encapsulated bacteria, notably Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenza [12,13]. Splenic dysfunction, therefore, leads to an increased susceptibility to encapsulated bacterial infections, notably pneumococcal infection. Indeed, T-independent clearance of polysaccharidic germs requires both an intact splenic filtration and an efficient opsonization by IgM antibodies.
Related Knowledge Centers
- Germinal Center
- Lymph Node
- Mantle Cell Lymphoma
- Lymphocyte
- Lymphoma
- Castleman Disease