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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 normal and mSLAM transfected L  cells, and the effects of mSLAM transfectants and sSLAM cross-linked to  polystyrene latex beads on B cell proliferation. Normal L cells (A) and L  cells transfected with cDNA encoding mSLAM (B) were stained with  PE-conjugated SLAM-specific mAb A12 (stippled histograms) or a PE-conjugated, isotype-matched control Ab with irrelevant specificity (open histograms), and the cells were analyzed by flow cytometry. (C ) Negatively selected B cells were cocultured in the presence or absence of irradiated  (7,300 rad) normal or SLAM transfected L cells (L-SLAM), anti-CD40  mAbs (10 μg/ml), IL-4 (100 U/ml), and/or IL-10 (100 U/ml) as indicated. Data represent mean ± SD of triplicate cultures in three separate  experiments. (D) Polystyrene latex beads coated with sSLAM by using  anti-Flag mAb M2 (SLAM-beads) were cocultured with purified B cells  under culture conditions indicated. Polystyrene latex beads coated with  only anti-Flag mAb (αFlag-beads) were used as controls. Proliferation was  measured by [3H]thymidine incorporation during the last 16 h of a 4-d  culture. Data represent mean ± SD of triplicate cultures.
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Figure 6: Expression of mSLAM on normal and mSLAM transfected L cells, and the effects of mSLAM transfectants and sSLAM cross-linked to polystyrene latex beads on B cell proliferation. Normal L cells (A) and L cells transfected with cDNA encoding mSLAM (B) were stained with PE-conjugated SLAM-specific mAb A12 (stippled histograms) or a PE-conjugated, isotype-matched control Ab with irrelevant specificity (open histograms), and the cells were analyzed by flow cytometry. (C ) Negatively selected B cells were cocultured in the presence or absence of irradiated (7,300 rad) normal or SLAM transfected L cells (L-SLAM), anti-CD40 mAbs (10 μg/ml), IL-4 (100 U/ml), and/or IL-10 (100 U/ml) as indicated. Data represent mean ± SD of triplicate cultures in three separate experiments. (D) Polystyrene latex beads coated with sSLAM by using anti-Flag mAb M2 (SLAM-beads) were cocultured with purified B cells under culture conditions indicated. Polystyrene latex beads coated with only anti-Flag mAb (αFlag-beads) were used as controls. Proliferation was measured by [3H]thymidine incorporation during the last 16 h of a 4-d culture. Data represent mean ± SD of triplicate cultures.

Mentions: To study the effects of mSLAM on B cell proliferation murine L cells were transfected with cDNA encoding mSLAM. Importantly, the transfectants expressed mSLAM at levels comparable to those on activated T cells (29) and B cells (Fig. 2 A), whereas untransfected L cells were completely mSLAM negative (Fig. 6, A and B). Irradiated mSLAM+ L cells strongly enhanced B cell proliferation induced by anti-CD40 mAbs in the presence of IL-4, IL-10 (Fig. 6 C), IL-2, or IL-15 (data not shown). Like sSLAM, mSLAM transfectants also enhanced proliferation of anti-CD40–activated B cells in the absence of exogenous cytokines.


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 normal and mSLAM transfected L  cells, and the effects of mSLAM transfectants and sSLAM cross-linked to  polystyrene latex beads on B cell proliferation. Normal L cells (A) and L  cells transfected with cDNA encoding mSLAM (B) were stained with  PE-conjugated SLAM-specific mAb A12 (stippled histograms) or a PE-conjugated, isotype-matched control Ab with irrelevant specificity (open histograms), and the cells were analyzed by flow cytometry. (C ) Negatively selected B cells were cocultured in the presence or absence of irradiated  (7,300 rad) normal or SLAM transfected L cells (L-SLAM), anti-CD40  mAbs (10 μg/ml), IL-4 (100 U/ml), and/or IL-10 (100 U/ml) as indicated. Data represent mean ± SD of triplicate cultures in three separate  experiments. (D) Polystyrene latex beads coated with sSLAM by using  anti-Flag mAb M2 (SLAM-beads) were cocultured with purified B cells  under culture conditions indicated. Polystyrene latex beads coated with  only anti-Flag mAb (αFlag-beads) were used as controls. Proliferation was  measured by [3H]thymidine incorporation during the last 16 h of a 4-d  culture. Data represent mean ± SD of triplicate cultures.
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Related In: Results  -  Collection

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Figure 6: Expression of mSLAM on normal and mSLAM transfected L cells, and the effects of mSLAM transfectants and sSLAM cross-linked to polystyrene latex beads on B cell proliferation. Normal L cells (A) and L cells transfected with cDNA encoding mSLAM (B) were stained with PE-conjugated SLAM-specific mAb A12 (stippled histograms) or a PE-conjugated, isotype-matched control Ab with irrelevant specificity (open histograms), and the cells were analyzed by flow cytometry. (C ) Negatively selected B cells were cocultured in the presence or absence of irradiated (7,300 rad) normal or SLAM transfected L cells (L-SLAM), anti-CD40 mAbs (10 μg/ml), IL-4 (100 U/ml), and/or IL-10 (100 U/ml) as indicated. Data represent mean ± SD of triplicate cultures in three separate experiments. (D) Polystyrene latex beads coated with sSLAM by using anti-Flag mAb M2 (SLAM-beads) were cocultured with purified B cells under culture conditions indicated. Polystyrene latex beads coated with only anti-Flag mAb (αFlag-beads) were used as controls. Proliferation was measured by [3H]thymidine incorporation during the last 16 h of a 4-d culture. Data represent mean ± SD of triplicate cultures.
Mentions: To study the effects of mSLAM on B cell proliferation murine L cells were transfected with cDNA encoding mSLAM. Importantly, the transfectants expressed mSLAM at levels comparable to those on activated T cells (29) and B cells (Fig. 2 A), whereas untransfected L cells were completely mSLAM negative (Fig. 6, A and B). Irradiated mSLAM+ L cells strongly enhanced B cell proliferation induced by anti-CD40 mAbs in the presence of IL-4, IL-10 (Fig. 6 C), IL-2, or IL-15 (data not shown). Like sSLAM, mSLAM transfectants also enhanced proliferation of anti-CD40–activated B cells in the absence of exogenous cytokines.

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