Peripheral development of B cells in mouse and man

Abstract

In man and in mouse, B-cell maturation occurs in steps, first in the bone marrow from hematopoietic precursors to immature/transitional B cells, then in the periphery from transitional to fully mature B cells. Each developmental step is tightly controlled by the expression and function of the B-cell receptor (BCR) and by the ability to interact with the microenvironment. Mature B cells collaborate with T cells in the adaptive immune response, leading to the production of high-affinity antibodies. This response is very accurate, but slow. Immediately after pathogen entry, however, antibodies already present in the serum reinforce the innate immune response and contribute to the first-line defense against infection. Low-affinity natural antibodies are produced by B-1a B cells in the mouse and immunoglobulin M (IgM) memory cells in man. These antibodies represent an immediate protection against all microorganisms and the only one against encapsulated bacteria. B-1a and IgM memory B cells may function as a link between the innate and adaptive immune response and thus perform a primordial B-cell function.

Proximal Versus Distal Splenic Artery Embolisation for Blunt Splenic Trauma: What is the Impact on Splenic Immune Function?

“…IgM memory B cell levels are reduced or absent in splenectomised and asplenic individuals [12,16,20,21]. A significant reduction or absence of IgM memory B cells is also found in patient groups with an intact spleen but known increased risk of invasive pneumococcal infection [18].…”

“…Production of natural antibody and innate immunity against bacterial infection has been attributed to B1 cells and to IgM Memory B cells which are found in the splenic marginal zone (SMZ) as well as in the peripheral blood, tonsils, and lymph nodes [16,17]. SMZ B cells require a functional spleen for optimal development and maintenance.…”

“…Unlike switched memory B cells, IgM memory B cells do not promote long-term protective humoral immune responses but give protection for approximately six months [21]. Deficiency or absence of IgM memory B cells is associated with increased frequency of pneumococcal infections and impaired response to polysaccharide pneumococcal vaccines [16].…”

CD5-positive follicular lymphoma: clinicopathologic correlations and outcome in 88 cases

“…15,16 In humans, CD5 induces an anergic state in lymphocytes and contributes to B-cell survival and interleukin-10 production, and CD5 expression on B-cells may serve as a marker of antigen exposure. 15,16 Assessment of CD5 expression by flow cytometry or immunohistochemistry has been widely used in the clinical work-up of B-cell lymphomas. CD5 expression is usually seen in chronic lymphocytic leukemia/small lymphocytic lymphoma or mantle cell lymphoma.…”

Defining a transcriptional fingerprint of murine splenic B-cell development

“…3,4 Autoreactive B cells are eliminated, undergo receptor editing, or are anergized in the marrow 5,6 and the spleen. 7,8 The most immature B cells of the spleen, termed transitional 1 cells (T1), 9 are susceptible to B-cell receptor-dependent cell death/arrest. On the basis of the models proposed by Loder, 10 Allman 11 and others, T1 cells lead to another transitional intermediate, the transition 2 (T2) cell.…”