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Soluble and membrane-bound forms of signaling lymphocytic activation molecule (SLAM) induce proliferation and Ig synthesis by activated human B lymphocytes.

Punnonen J, Cocks BG, Carballido JM, Bennett B, Peterson D, Aversa G, de Vries JE - J. Exp. Med. (1997)

Bottom Line: Activated B cells express the membrane-bound form of SLAM (mSLAM), the soluble (s) and the cytoplasmic (c) isoforms of SLAM, and the expression levels of mSLAM on B cells are rapidly upregulated after activation in vitro.In addition, sSLAM enhances production of IgM, IgG, and IgA by B cells activated by anti-CD40 mAbs.SLAM has recently been shown to be a high affinity self-ligand, and the present data suggest that signaling through homophilic SLAM-SLAM binding during B-B and B-T cell interactions enhances the expansion and differentiation of activated B cells.

View Article: PubMed Central - PubMed

Affiliation: Department of Human Immunology, DNAX Research Institute of Molecular and Cellular Biology, Palo Alto, California 94304, USA.

ABSTRACT
In this study it is shown that both membrane-bound and soluble forms of signaling lymphocytic activation molecule (SLAM) induce proliferation and Ig synthesis by activated human B cells. Activated B cells express the membrane-bound form of SLAM (mSLAM), the soluble (s) and the cytoplasmic (c) isoforms of SLAM, and the expression levels of mSLAM on B cells are rapidly upregulated after activation in vitro. Importantly, recombinant sSLAM and L cells transfected with mSLAM efficiently enhance B cell proliferation induced by anti-mu mAbs, anti-CD40 mAbs or Staphylococcus aureus Cowan I (SAC) in the presence or absence of IL-2, IL-4, IL-10, IL-12, or IL-15. sSLAM strongly enhances proliferation of both freshly isolated B cells and B cells derived from long-term in vitro cultures, indicating that SLAM acts not only during the initial phase of B cell activation but also during the expansion of preactivated B cells. In addition, sSLAM enhances production of IgM, IgG, and IgA by B cells activated by anti-CD40 mAbs. SLAM has recently been shown to be a high affinity self-ligand, and the present data suggest that signaling through homophilic SLAM-SLAM binding during B-B and B-T cell interactions enhances the expansion and differentiation of activated B cells.

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Expression of mSLAM on PB and splenic B cells. PB (a–e) or splenic (f–j) B cells were stained with FITC-conjugated anti-CD20 mAbs and  PE-conjugated anti-SLAM mAb A12 (open histograms) or PE-conjugated mouse IgG1 Ab with irrelevant specificity (stippled histograms). CD20+ cells were  gated and expression of mSLAM was studied by flow cytometry. All histograms represent stainings of cells derived from different donors. PB B cells in a–d  were first enriched for B cells by depleting T cells, NK cells and monocytes by magnetic beads. Dead cells were always excluded by gating out PI+ cells.
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Figure 1: Expression of mSLAM on PB and splenic B cells. PB (a–e) or splenic (f–j) B cells were stained with FITC-conjugated anti-CD20 mAbs and PE-conjugated anti-SLAM mAb A12 (open histograms) or PE-conjugated mouse IgG1 Ab with irrelevant specificity (stippled histograms). CD20+ cells were gated and expression of mSLAM was studied by flow cytometry. All histograms represent stainings of cells derived from different donors. PB B cells in a–d were first enriched for B cells by depleting T cells, NK cells and monocytes by magnetic beads. Dead cells were always excluded by gating out PI+ cells.

Mentions: The expression of mSLAM on peripheral blood (PB) and splenic B cells was studied by double immunofluorescence using mAbs specific for CD20 and SLAM (29). The expression level of SLAM was generally higher on PB B cells than on splenic B cells (Fig. 1). The percentages of SLAM+ cells among PB B cells ranged between 20 and 50%, whereas those among splenic B cells were generally less than 20%. B cells were rather homogenous in terms of their SLAM expression, and staining with SLAM-specific mAb generally caused a shift in the staining pattern rather than resulted in the detection of two separate populations of positive and negative cells (Fig. 1). Because of the low proportion of B cells in PB mononuclear cells (MC), in some experiments B cells were first enriched by depleting T cells, NK cells and monocytes by magnetic beads. The results using total splenic MC or PBMC were comparable to those using B cell enriched cell populations (Fig. 1 and data not shown), indicating that cell purification method did not affect the results.


Soluble and membrane-bound forms of signaling lymphocytic activation molecule (SLAM) induce proliferation and Ig synthesis by activated human B lymphocytes.

Punnonen J, Cocks BG, Carballido JM, Bennett B, Peterson D, Aversa G, de Vries JE - J. Exp. Med. (1997)

Expression of mSLAM on PB and splenic B cells. PB (a–e) or splenic (f–j) B cells were stained with FITC-conjugated anti-CD20 mAbs and  PE-conjugated anti-SLAM mAb A12 (open histograms) or PE-conjugated mouse IgG1 Ab with irrelevant specificity (stippled histograms). CD20+ cells were  gated and expression of mSLAM was studied by flow cytometry. All histograms represent stainings of cells derived from different donors. PB B cells in a–d  were first enriched for B cells by depleting T cells, NK cells and monocytes by magnetic beads. Dead cells were always excluded by gating out PI+ cells.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2196230&req=5

Figure 1: Expression of mSLAM on PB and splenic B cells. PB (a–e) or splenic (f–j) B cells were stained with FITC-conjugated anti-CD20 mAbs and PE-conjugated anti-SLAM mAb A12 (open histograms) or PE-conjugated mouse IgG1 Ab with irrelevant specificity (stippled histograms). CD20+ cells were gated and expression of mSLAM was studied by flow cytometry. All histograms represent stainings of cells derived from different donors. PB B cells in a–d were first enriched for B cells by depleting T cells, NK cells and monocytes by magnetic beads. Dead cells were always excluded by gating out PI+ cells.
Mentions: The expression of mSLAM on peripheral blood (PB) and splenic B cells was studied by double immunofluorescence using mAbs specific for CD20 and SLAM (29). The expression level of SLAM was generally higher on PB B cells than on splenic B cells (Fig. 1). The percentages of SLAM+ cells among PB B cells ranged between 20 and 50%, whereas those among splenic B cells were generally less than 20%. B cells were rather homogenous in terms of their SLAM expression, and staining with SLAM-specific mAb generally caused a shift in the staining pattern rather than resulted in the detection of two separate populations of positive and negative cells (Fig. 1). Because of the low proportion of B cells in PB mononuclear cells (MC), in some experiments B cells were first enriched by depleting T cells, NK cells and monocytes by magnetic beads. The results using total splenic MC or PBMC were comparable to those using B cell enriched cell populations (Fig. 1 and data not shown), indicating that cell purification method did not affect the results.

Bottom Line: Activated B cells express the membrane-bound form of SLAM (mSLAM), the soluble (s) and the cytoplasmic (c) isoforms of SLAM, and the expression levels of mSLAM on B cells are rapidly upregulated after activation in vitro.In addition, sSLAM enhances production of IgM, IgG, and IgA by B cells activated by anti-CD40 mAbs.SLAM has recently been shown to be a high affinity self-ligand, and the present data suggest that signaling through homophilic SLAM-SLAM binding during B-B and B-T cell interactions enhances the expansion and differentiation of activated B cells.

View Article: PubMed Central - PubMed

Affiliation: Department of Human Immunology, DNAX Research Institute of Molecular and Cellular Biology, Palo Alto, California 94304, USA.

ABSTRACT
In this study it is shown that both membrane-bound and soluble forms of signaling lymphocytic activation molecule (SLAM) induce proliferation and Ig synthesis by activated human B cells. Activated B cells express the membrane-bound form of SLAM (mSLAM), the soluble (s) and the cytoplasmic (c) isoforms of SLAM, and the expression levels of mSLAM on B cells are rapidly upregulated after activation in vitro. Importantly, recombinant sSLAM and L cells transfected with mSLAM efficiently enhance B cell proliferation induced by anti-mu mAbs, anti-CD40 mAbs or Staphylococcus aureus Cowan I (SAC) in the presence or absence of IL-2, IL-4, IL-10, IL-12, or IL-15. sSLAM strongly enhances proliferation of both freshly isolated B cells and B cells derived from long-term in vitro cultures, indicating that SLAM acts not only during the initial phase of B cell activation but also during the expansion of preactivated B cells. In addition, sSLAM enhances production of IgM, IgG, and IgA by B cells activated by anti-CD40 mAbs. SLAM has recently been shown to be a high affinity self-ligand, and the present data suggest that signaling through homophilic SLAM-SLAM binding during B-B and B-T cell interactions enhances the expansion and differentiation of activated B cells.

Show MeSH
Related in: MedlinePlus