Ontogeny of B Lymphocytes

Abstract

The class of mammalian lymphocytes equivalent to the bursa-derived (B) 1 lymphocytes of birds may be identified by the presence of large amounts of immunoglobulin (Ig) on the surface of most of these cells (1, 2). In addition, many of these B lymphocytes, but not thymus-derived (T) lymphocytes, bear a surface receptor for an activated component of C3 allowing them to bind antigen-antibody-complement complexes (3). These cells are referred to as complement receptor lymphocytes (CRL).Although no functional role for the C receptor of B lymphocytes has yet been established, at least two major possibilities have been suggested. Firstly, the C receptor by binding antigen-antibody-complement complexes may serve as an antigen concentrating mechanism and thus increase the likelihood that antigens would interact with with specific receptors on the surface of immunocompetent B lymphocytes and then activate these cells (4). Alternatively, it has been proposed that B-lymphocyte activation requires the interaction of that cell both with specific antigen and with another ligand leading to the generation of two signals within the cell. A major candidate for the ligand generating the so-called "second signal" would be activated C3 binding to to the C receptor (5). In such a model the binding of activated C3 would be crucial to B-cell stimulation.

Differences in susceptibility of mature and immature mouse B lymphocytes to anti-immunoglobulin-induced immunoglobulin suppression in vitro. Possible implications for B-cell tolerance to self.

“…Whether this apparent maturation from "high Ig suppressibility" to "low suppressibility" is antigen driven, and whether it requires T cells and/or migration from the sites of production to the microenvironment of the peripheral lymphoid tissues, remains to be determined. It is also unclear how it relates to other parameters of B-cell maturation that have been described, such as changes in generation time (33), cell density and size (21,33), Ig receptor turnover (21), response to B-cell mitogens (21), or the acquisition of surface IgD (1,37) or complement receptors (8) .…”

B-lymphocyte heterogeneity: development and characterization of an alloantiserum which distinguishes B-lymphocyte differentiation alloantigens.

“…Previous work in our laboratory has demonstrated that CBA/N mice and F, male mice derived from crosses of CBA/N female mice with normal male mice (14), (b) the minor lymphocyte stimulating (Mls) coded lymphocyte-activating determinants (LADs) (12)(13)(14)(15)(16)(17), (c) a low density of IgM (2), (d) a low-to-intermediate density of total Ig (2), and (e) a relatively low ratio of surface IgM to IgD (9). The apparent absence of this B-lymphocyte subpopulation in CBA/N mice presented an opportunity to develop an antiserum directed against differentiation antigens unique to these cells (2,(9)(10)(11)(12).…”

“…Ig + spleen cell suspensions (5 x 10~/ml), obtained from the FACS, were mixed with an equal vol (0.4 ml) of sheep erythrocytes coated with anti-Forssman antibody and complement (EAC) reagent (14) for 45 min at 37°C. The mixture was then layered on Ficoll-Hypaque (specific grade 1.094) and centrifuged for 30 min at 450g.…”

Ontogeny of mouse lymphocyte function. II. Development of the ability to produce antibody is modulated by T lymphocytes.

“…This failure of the immune response to occur is puzzling since spleen cells from mice 2 or 3 wk old possess normal adult numbers of 0-bearing T lymphocytes (1, 2) and immunoglobulin-bearing B lymphocytes (1,3) .…”