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S A Shinton

Publications and source records attributed to S A Shinton.

8 recordsLinked to original sources
PubMed1998

A novel mechanism for B cell repertoire maturation based on response by B cell precursors to pre-B receptor assembly.

The expression of different sets of immunoglobulin specificities by fetal and adult B lymphocytes is a long-standing puzzle in immunology. Recently it has become clear that production of immunoglobulin mu heavy chain and subsequent assembly with a surrogate light chain to form the pre-B cell receptor complex is critical for development of B cells. Here we show that instead of promoting pre-B cell progression as in adult bone marrow, this complex inhibits pre-B cell growth in fetal liver. Curiously, we identify a fetal-associated VH11 mu heavy chain that allows continued pre-B proliferation in fetal liver. Interestingly, this heavy chain does not associate efficiently with a surrogate light chain, providing a previously unrecognized mechanism for skewing the expression of distinctive VH genes toward fetal through early neonatal life.

Animals↗
PubMed1997

Both E12 and E47 allow commitment to the B cell lineage.

The E2A gene products, E12 and E47, are required for proper B cell development. Mice lacking the E2A gene products generate only a very small number of B220+ cells, which lack immunoglobulin DJ(H) rearrangements. We have now generated mice expressing either E12 or E47. B cell development in mice expressing E12 but lacking E47 is perturbed at the pro-B cell stage, and these mice lack IgM+B220+ B cells in both bone marrow and spleen. IgM+B220+ B cells can be detected, albeit at significantly reduced levels, in the bone marrow and spleen of mice lacking E12. Ectopic expression of both E12 and E47 in a null mutant background shows that E12 and E47 act in concert to promote B lineage development. Taken together, the data indicate that both E12 and E47 allow commitment to the B cell lineage and act synergistically to promote B lymphocyte maturation.

Animals↗
PubMed1994

Functional immunoglobulin transgenes guide ordered B-cell differentiation in Rag-1-deficient mice.

We have examined the regulatory role of the individual components of the immunoglobulin antigen receptor in B-cell development by transgenic complementation of Rag-1 deficient (Rag-1-) mice. Complementation with a membrane mu heavy chain (mu HC) gene allows progression of developmentally arrested Rag-1- pro-B-cells to the small pre-B cell stage, whereas the introduction of independently integrated mu HC and kappa light chain (kappa LC) transgenes promotes the appearance of peripheral lymphocytes which, however, remain unresponsive to external stimuli. Complete reconstitution of the B-cell lineage and the emergence of functionally nature Rag-1- peripheral B cells is achieved by the introduction of cointegrated heavy and light chain transgenes encoding an anti-H-2k antibody. This experimental system demonstrates the competence of the mu HC and kappa LC to direct and regulate the sequential stages of B-cell differentiation, defines the time at which negative selection of self-reactive B cells occurs, and shows that elimination of these cells occurs equally well in the absence of Rag-1 as in its presence. These data also support the hypothesis that Rag-1 directly participates in the V(D)J recombination process.

Animals↗
PubMed1991

Resolution and characterization of pro-B and pre-pro-B cell stages in normal mouse bone marrow.

We have resolved B220+ IgM- B-lineage cells in mouse bone marrow into four fractions based on differential cell surface expression of determinants recognized by S7 (leukosialin, CD43), BP-1, and 30F1 (heat stable antigen). Functional differences among these fractions can be correlated with Ig gene rearrangement status. The largest fraction, lacking S7, consists of pre-B cells whereas the others, expressing S7, include B lineage cells before pre-B. These S7+ fractions, provisionally termed Fr. A, Fr. B, and Fr. C, can differentiate in a stromal layer culture system. Phenotypic alteration during such culture suggests an ordering of these stages from Fr. A to Fr. B to Fr. C and thence to S7- pre-B cells. Using polymerase chain reaction amplification with pairs of oligonucleotide primers for regions 5' of JH1, DFL16.1, and Jk1, we find that the Ig genes of Fr. A are in germline configuration, whereas Fr. B and C are pro-B cell stages with increasing D-J rearrangement, but no V-D-J. Finally, functional analysis demonstrates that the proliferative response to IL-7, an early B lineage growth factor, is restricted to S7+ stages and, furthermore, that an additional, cell contact-mediated signal is essential for survival of Fr. A.

Animals↗
PubMed1990

Rearrangement and selection of VH11 in the Ly-1 B cell lineage.

One of the predominant VH genes utilized to encode the anti-BrMRBC specificity is a member of the small VH11 family rearranged to JH1. Using the polymerase chain reaction (PCR) we have determined that the frequency of B cells with a VH11 rearrangement is 10-20 times higher in Ly-1 B than in Ly-1- "conventional" B cells regardless of location (spleen or peritoneal cavity). Conventional B cells rearrange this gene at comparable levels in pre-B cells and in mature B cells utilizing all JH gene segments. In contrast, the increased levels of VH11 rearrangement in Ly-1 B are restricted to JH1 (and some JH2) and therefore appear to be the result of selection. Furthermore, most peritoneal Ly-1 B cells with VH11 rearrangements fall in a fraction stained by anti-BrMRBC antibody, likely bearing multivalent natural (likely self) antigen constitutively bound to their surface Ig receptors. Thus, we suggest that autoantigens are largely responsible for the accumulation of autoantibody specificities in the Ly-1 B cell lineage with time, whereas they do not exert this effect in the conventional B cells.

Animals↗
PubMed1989

A single VH gene is utilized predominantly in anti-BrMRBC hybridomas derived from purified Ly-1 B cells. Definition of the VH11 family.

By establishing hybridomas from two distinct surface IgM+ splenic B cell populations, Ly-1 B cells and "conventional" (Ly-1-) B cells, we found that the Ly-1 B population includes a 30 to 70 times higher frequency (1 to 2%) of cells with specificity for bromelain treated autologous red blood cells (anti-BrMRBC) when compared with conventional B cells (0.03%). We cloned and sequenced the V genes encoding anti-BrMRBC antibody from two hybridomas made with Ly-1 B cells sorted from the spleen of SM/J mice. The VH sequence (for both) is identical with the previously reported sequence associated with this specificity and belongs to a new VH gene family. This gene family, defined here as VH11, has only two members and is the predominant VH rearranged in a collection of Ly-1 B derived anti-BrMRBC hybridomas, always in association with a single VL gene (a member of the V kappa 9 family). Furthermore, analysis of hybridomas made with Ly-1 B cells sorted from the peritoneum reveals a yet higher increased frequency of VH11-encoded anti-BrMRBC specificity (30%). This variation in frequency of anti-BrMRBC in the Ly-1 population depending on location, together with the repeated association of VH11 with a particular V kappa gene suggest that antigen driven selection is (at least in part) responsible for the biased V gene expression seen in this population. Furthermore, a mechanism that might contribute to biased expression, preferential rearrangement due to close proximity to J (as seen in pre-B lines), is excluded by localization of VH11 5' to several of the more J-proximal families (Q52, 7183).

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