The Experts below are selected from a list of 24 Experts worldwide ranked by ideXlab platform

Garnett Kelsoe - One of the best experts on this subject based on the ideXlab platform.

  • in situ studies of the primary immune response to 4 hydroxy 3 nitrophenyl acetyl ii a common clonal origin for Periarteriolar Lymphoid sheath associated foci and germinal centers
    Journal of Experimental Medicine, 1992
    Co-Authors: Joshy Jacob, Garnett Kelsoe
    Abstract:

    In the genetically restricted response that follows immunization with (4-hydroxy-3-nitrophenyl)acetyl coupled to protein carriers, two distinct populations of B cells are observed in the spleens of C57BL/6 mice. By 48 h postimmunization, foci of antigen-binding B cells appear along the periphery of the Periarteriolar Lymphoid Sheaths. These foci expand to contain large numbers of antibody-forming cells that neither bind the lectin, peanut agglutinin, nor mutate the rearranged immunoglobulin variable region loci. Germinal centers containing peanut agglutinin-positive B cells can be observed by 96-120 h after immunization. Although specific for the immunizing hapten, these B cells do not produce substantial amounts of antibody, but are the population that undergoes somatic hypermutation and affinity-driven selection. Both focus and germinal center populations are pauciclonal, founded, on average, by three or fewer B lymphocytes. Despite the highly specialized roles of the focus (early antibody production) and germinal center (higher affinity memory cells) B cell populations, analysis of VH to D to JH joins in neighboring foci and germinal centers demonstrate that these B cell populations have a common clonal origin.

  • in situ studies of the primary immune response to 4 hydroxy 3 nitrophenyl acetyl i the architecture and dynamics of responding cell populations
    Journal of Experimental Medicine, 1991
    Co-Authors: Joshy Jacob, R Kassir, Garnett Kelsoe
    Abstract:

    After primary immunization with an immunogenic conjugate of (4-hydroxy-3-nitrophenyl)acetyl, two anatomically and phenotypically distinct populations of antibody-forming cells arise in the spleen. As early as 2 d after immunization, foci of antigen-binding B cells are observed along the periphery of the Periarteriolar Lymphoid Sheaths. These foci expand, occupying as much as 1% of the splenic volume by day 8 of the response. Later, foci grow smaller and are virtually absent from the spleen by day 14. A second responding population, germinal center B cells, appear on day 8-10 and persist at least until day 16 post-immunization. Individual foci and germinal centers represent discrete pauciclonal populations that apparently undergo somatic evolution in the course of the primary response. We suggest that foci may represent regions of predominantly interclonal competition for antigen among unmutated B cells, while germinal centers are sites of intraclonal clonal competition between mutated sister lymphocytes.

Joshy Jacob - One of the best experts on this subject based on the ideXlab platform.

  • in situ studies of the primary immune response to 4 hydroxy 3 nitrophenyl acetyl ii a common clonal origin for Periarteriolar Lymphoid sheath associated foci and germinal centers
    Journal of Experimental Medicine, 1992
    Co-Authors: Joshy Jacob, Garnett Kelsoe
    Abstract:

    In the genetically restricted response that follows immunization with (4-hydroxy-3-nitrophenyl)acetyl coupled to protein carriers, two distinct populations of B cells are observed in the spleens of C57BL/6 mice. By 48 h postimmunization, foci of antigen-binding B cells appear along the periphery of the Periarteriolar Lymphoid Sheaths. These foci expand to contain large numbers of antibody-forming cells that neither bind the lectin, peanut agglutinin, nor mutate the rearranged immunoglobulin variable region loci. Germinal centers containing peanut agglutinin-positive B cells can be observed by 96-120 h after immunization. Although specific for the immunizing hapten, these B cells do not produce substantial amounts of antibody, but are the population that undergoes somatic hypermutation and affinity-driven selection. Both focus and germinal center populations are pauciclonal, founded, on average, by three or fewer B lymphocytes. Despite the highly specialized roles of the focus (early antibody production) and germinal center (higher affinity memory cells) B cell populations, analysis of VH to D to JH joins in neighboring foci and germinal centers demonstrate that these B cell populations have a common clonal origin.

  • in situ studies of the primary immune response to 4 hydroxy 3 nitrophenyl acetyl i the architecture and dynamics of responding cell populations
    Journal of Experimental Medicine, 1991
    Co-Authors: Joshy Jacob, R Kassir, Garnett Kelsoe
    Abstract:

    After primary immunization with an immunogenic conjugate of (4-hydroxy-3-nitrophenyl)acetyl, two anatomically and phenotypically distinct populations of antibody-forming cells arise in the spleen. As early as 2 d after immunization, foci of antigen-binding B cells are observed along the periphery of the Periarteriolar Lymphoid Sheaths. These foci expand, occupying as much as 1% of the splenic volume by day 8 of the response. Later, foci grow smaller and are virtually absent from the spleen by day 14. A second responding population, germinal center B cells, appear on day 8-10 and persist at least until day 16 post-immunization. Individual foci and germinal centers represent discrete pauciclonal populations that apparently undergo somatic evolution in the course of the primary response. We suggest that foci may represent regions of predominantly interclonal competition for antigen among unmutated B cells, while germinal centers are sites of intraclonal clonal competition between mutated sister lymphocytes.

R Kassir - One of the best experts on this subject based on the ideXlab platform.

  • in situ studies of the primary immune response to 4 hydroxy 3 nitrophenyl acetyl i the architecture and dynamics of responding cell populations
    Journal of Experimental Medicine, 1991
    Co-Authors: Joshy Jacob, R Kassir, Garnett Kelsoe
    Abstract:

    After primary immunization with an immunogenic conjugate of (4-hydroxy-3-nitrophenyl)acetyl, two anatomically and phenotypically distinct populations of antibody-forming cells arise in the spleen. As early as 2 d after immunization, foci of antigen-binding B cells are observed along the periphery of the Periarteriolar Lymphoid Sheaths. These foci expand, occupying as much as 1% of the splenic volume by day 8 of the response. Later, foci grow smaller and are virtually absent from the spleen by day 14. A second responding population, germinal center B cells, appear on day 8-10 and persist at least until day 16 post-immunization. Individual foci and germinal centers represent discrete pauciclonal populations that apparently undergo somatic evolution in the course of the primary response. We suggest that foci may represent regions of predominantly interclonal competition for antigen among unmutated B cells, while germinal centers are sites of intraclonal clonal competition between mutated sister lymphocytes.

Ronald N Germain - One of the best experts on this subject based on the ideXlab platform.

  • analysis of adjuvant function by direct visualization of antigen presentation in vivo endotoxin promotes accumulation of antigen bearing dendritic cells in the t cell areas of Lymphoid tissue
    Journal of Immunology, 1999
    Co-Authors: Reis C E Sousa, Ronald N Germain
    Abstract:

    T cell activation requires exposure to processed Ag and signaling by cytokines and costimulatory ligands. Adjuvants are thought to enhance immunity primarily through up-regulation of the latter signals. Here, we explore the effect of the bacterial adjuvant, endotoxin, on Ag presentation by B cells and dendritic cells (DC). Using an mAb (C4H3) specific for the hen egg lysozyme (HEL) 46-61 determinant bound to I-Ak, we analyze processed Ag expression and the tissue distribution of presenting cells following systemic administration of soluble HEL to mice. In both LPS-responsive and -hyporesponsive mice given endotoxin-containing HEL, B cells rapidly display surface 46-61/I-Ak complexes. In marked contrast, in LPS-hyporesponsive mice, splenic DC show little gain in C4H3 staining. In LPS-responsive animals, interdigitating DC in T cell areas show no staining above background at early times after HEL administration, but C4H3+ DC rapidly accumulate in the outer Periarteriolar Lymphoid Sheaths (PALS) and in follicular areas. Within a few hours, C4H3+ DC appear in the T cell areas, concomitant with a decline in C4H3+ cells in the outer PALS, suggesting migration between these two sites. Endotoxin enhancement of C4H3 staining is seen for both CD8α− and CD8α+ DC subsets. These data suggest that a major effect of adjuvants is to promote mobilization of Ag-bearing DC to the T areas of Lymphoid tissue, and possibly also to enhance Ag processing by these DC. Thus, microbial products promote T cell immunity not only through DC activation for cosignaling, but through improvement in signal 1 delivery.

Reis C E Sousa - One of the best experts on this subject based on the ideXlab platform.

  • analysis of adjuvant function by direct visualization of antigen presentation in vivo endotoxin promotes accumulation of antigen bearing dendritic cells in the t cell areas of Lymphoid tissue
    Journal of Immunology, 1999
    Co-Authors: Reis C E Sousa, Ronald N Germain
    Abstract:

    T cell activation requires exposure to processed Ag and signaling by cytokines and costimulatory ligands. Adjuvants are thought to enhance immunity primarily through up-regulation of the latter signals. Here, we explore the effect of the bacterial adjuvant, endotoxin, on Ag presentation by B cells and dendritic cells (DC). Using an mAb (C4H3) specific for the hen egg lysozyme (HEL) 46-61 determinant bound to I-Ak, we analyze processed Ag expression and the tissue distribution of presenting cells following systemic administration of soluble HEL to mice. In both LPS-responsive and -hyporesponsive mice given endotoxin-containing HEL, B cells rapidly display surface 46-61/I-Ak complexes. In marked contrast, in LPS-hyporesponsive mice, splenic DC show little gain in C4H3 staining. In LPS-responsive animals, interdigitating DC in T cell areas show no staining above background at early times after HEL administration, but C4H3+ DC rapidly accumulate in the outer Periarteriolar Lymphoid Sheaths (PALS) and in follicular areas. Within a few hours, C4H3+ DC appear in the T cell areas, concomitant with a decline in C4H3+ cells in the outer PALS, suggesting migration between these two sites. Endotoxin enhancement of C4H3 staining is seen for both CD8α− and CD8α+ DC subsets. These data suggest that a major effect of adjuvants is to promote mobilization of Ag-bearing DC to the T areas of Lymphoid tissue, and possibly also to enhance Ag processing by these DC. Thus, microbial products promote T cell immunity not only through DC activation for cosignaling, but through improvement in signal 1 delivery.