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Human dendritic cells skew isotype switching of CD40-activated naive B cells towards IgA1 and IgA2.

Fayette J, Dubois B, Vandenabeele S, Bridon JM, Vanbervliet B, Durand I, Banchereau J, Caux C, Brière F - J. Exp. Med. (1997)

Bottom Line: D-Lc alone did not induce the secretion of IgA by CD40-activated naive B cells, which required further addition of IL-10.In the presence of IL-10, secretion of IgA2 by CD40-activated naive B cells could be detected only in response to D-Lc and was further enhanced by TGF-beta.Collectively, these results suggest that in addition to activating T cells in the extrafollicular areas of secondary lymphoid organs, human D-Lc also directly modulate T cell-dependent B cell growth and differentiation, by inducing the IgA isotype switch.

View Article: PubMed Central - PubMed

Affiliation: Schering-Plough, Laboratory for Immunological Research, Dardilly, France.

ABSTRACT
Within T cell-rich areas of secondary lymphoid organs, interdigitating dendritic cells recruit antigen-specific T cells that then induce B cells to secrete Igs. This study investigates the possible role(s) of dendritic cells in the regulation of human B cell responses. In the absence of exogenous cytokines, in vitro generated dendritic cells (referred to as Dendritic Langerhans cells, D-Lc) induced surface IgA expression on approximately 10% of CD40-activated naive sIgD+ B cells. In the presence of IL-10 and TGF-beta, a combination of cytokines previously identified for its capacity to induce IgA switch, D-Lc strongly potentiated the induction of sIgA on CD40-activated naive B cells from 5% to 40-50%. D-Lc alone did not induce the secretion of IgA by CD40-activated naive B cells, which required further addition of IL-10. Furthermore, D-Lc skewed towards the IgA isotype at the expense of IgG, the Ig production of CD40-activated naive B cells cultured in the presence of IL-10 and TGF-beta. Importantly, under these culture conditions, both IgA1 and IgA2 were detected. In the presence of IL-10, secretion of IgA2 by CD40-activated naive B cells could be detected only in response to D-Lc and was further enhanced by TGF-beta. Collectively, these results suggest that in addition to activating T cells in the extrafollicular areas of secondary lymphoid organs, human D-Lc also directly modulate T cell-dependent B cell growth and differentiation, by inducing the IgA isotype switch.

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D-Lc induce CD40-activated naive B cells to express sIgA. 5 ×  104/ml sIgD+ B lymphocytes were cultured in a final volume of 1 ml in  the absence or presence of 5 × 104/ml D-Lc over 1.25 × 104/ml irradiated CD40L-L cells without exogenous cytokine or with IL-10 (200 ng/ ml), TGF-β (0.3 ng/ml) or both (A), or with IL-10 and increasing doses  of TGF-β (B). B cells were harvested after 7 d of culture and stained with  rabbit polyclonal FITC-labeled anti-IgA or anti-IgG antibodies (A, B) or  FITC-labeled anti-IgA1 or -IgA2 mAbs (C) and analyzed by FACScan®.  Dead cells which incorporated propidium iodide were excluded. Histograms are presented (A) or percentages of sIgG and sIgA positively stained  cells (B). One representative experiment out of six (A) and one out of  three (B) are shown.
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Figure 3: D-Lc induce CD40-activated naive B cells to express sIgA. 5 × 104/ml sIgD+ B lymphocytes were cultured in a final volume of 1 ml in the absence or presence of 5 × 104/ml D-Lc over 1.25 × 104/ml irradiated CD40L-L cells without exogenous cytokine or with IL-10 (200 ng/ ml), TGF-β (0.3 ng/ml) or both (A), or with IL-10 and increasing doses of TGF-β (B). B cells were harvested after 7 d of culture and stained with rabbit polyclonal FITC-labeled anti-IgA or anti-IgG antibodies (A, B) or FITC-labeled anti-IgA1 or -IgA2 mAbs (C) and analyzed by FACScan®. Dead cells which incorporated propidium iodide were excluded. Histograms are presented (A) or percentages of sIgG and sIgA positively stained cells (B). One representative experiment out of six (A) and one out of three (B) are shown.

Mentions: After 7 d of CD40 activation, the frequency of cultured naive B cells expressing sIgA was always lower than 1–2% (Fig. 3 A). Upon addition of either DC alone or a combination of TGF-β and IL-10, 6.5–10% of naive B cells expressed sIgA. Neither IL-10 nor TGF-β alone were able to induce naive B cells to express sIgA. However IL-10, and to a lower extent TGF-β, can enhance sIgA expression induced by D-Lc. D-Lc potentiated strikingly the induction of sIgA on CD40activated naive B cells induced by a combination of IL-10 and TGF-β from 6.5 up to 41.7% (mean 35 ± 15%, n = 6). 0.3 ng/ml of TGF-β induced an optimal increase of the frequency of sIgA B cells generated in response to D-Lc and IL-10 (Fig. 3 B). With regard to sIgG, IL-10 alone appeared to be a strong inducer (from 3.3 to 11.6%), whereas D-Lc alone displayed virtually no effect. Yet, D-Lc enhanced IL-10 induced expression of sIgG (from 11.6 to 16.9%) (Fig. 3 A). Importantly, D-Lc with TGF-β, inhibited IL-10–induced sIgG expression at concentrations that stimulated sIgA expression (Fig. 3 B). Further analysis of the sIgA subclasses shows that 18.8% of CD40-activated naive B cells expressed sIgA1, whereas 7.9% expressed sIgA2 after culture in the presence of IL-10, TGF-β, and D-Lc (Fig. 3 C).


Human dendritic cells skew isotype switching of CD40-activated naive B cells towards IgA1 and IgA2.

Fayette J, Dubois B, Vandenabeele S, Bridon JM, Vanbervliet B, Durand I, Banchereau J, Caux C, Brière F - J. Exp. Med. (1997)

D-Lc induce CD40-activated naive B cells to express sIgA. 5 ×  104/ml sIgD+ B lymphocytes were cultured in a final volume of 1 ml in  the absence or presence of 5 × 104/ml D-Lc over 1.25 × 104/ml irradiated CD40L-L cells without exogenous cytokine or with IL-10 (200 ng/ ml), TGF-β (0.3 ng/ml) or both (A), or with IL-10 and increasing doses  of TGF-β (B). B cells were harvested after 7 d of culture and stained with  rabbit polyclonal FITC-labeled anti-IgA or anti-IgG antibodies (A, B) or  FITC-labeled anti-IgA1 or -IgA2 mAbs (C) and analyzed by FACScan®.  Dead cells which incorporated propidium iodide were excluded. Histograms are presented (A) or percentages of sIgG and sIgA positively stained  cells (B). One representative experiment out of six (A) and one out of  three (B) are shown.
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Related In: Results  -  Collection

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Figure 3: D-Lc induce CD40-activated naive B cells to express sIgA. 5 × 104/ml sIgD+ B lymphocytes were cultured in a final volume of 1 ml in the absence or presence of 5 × 104/ml D-Lc over 1.25 × 104/ml irradiated CD40L-L cells without exogenous cytokine or with IL-10 (200 ng/ ml), TGF-β (0.3 ng/ml) or both (A), or with IL-10 and increasing doses of TGF-β (B). B cells were harvested after 7 d of culture and stained with rabbit polyclonal FITC-labeled anti-IgA or anti-IgG antibodies (A, B) or FITC-labeled anti-IgA1 or -IgA2 mAbs (C) and analyzed by FACScan®. Dead cells which incorporated propidium iodide were excluded. Histograms are presented (A) or percentages of sIgG and sIgA positively stained cells (B). One representative experiment out of six (A) and one out of three (B) are shown.
Mentions: After 7 d of CD40 activation, the frequency of cultured naive B cells expressing sIgA was always lower than 1–2% (Fig. 3 A). Upon addition of either DC alone or a combination of TGF-β and IL-10, 6.5–10% of naive B cells expressed sIgA. Neither IL-10 nor TGF-β alone were able to induce naive B cells to express sIgA. However IL-10, and to a lower extent TGF-β, can enhance sIgA expression induced by D-Lc. D-Lc potentiated strikingly the induction of sIgA on CD40activated naive B cells induced by a combination of IL-10 and TGF-β from 6.5 up to 41.7% (mean 35 ± 15%, n = 6). 0.3 ng/ml of TGF-β induced an optimal increase of the frequency of sIgA B cells generated in response to D-Lc and IL-10 (Fig. 3 B). With regard to sIgG, IL-10 alone appeared to be a strong inducer (from 3.3 to 11.6%), whereas D-Lc alone displayed virtually no effect. Yet, D-Lc enhanced IL-10 induced expression of sIgG (from 11.6 to 16.9%) (Fig. 3 A). Importantly, D-Lc with TGF-β, inhibited IL-10–induced sIgG expression at concentrations that stimulated sIgA expression (Fig. 3 B). Further analysis of the sIgA subclasses shows that 18.8% of CD40-activated naive B cells expressed sIgA1, whereas 7.9% expressed sIgA2 after culture in the presence of IL-10, TGF-β, and D-Lc (Fig. 3 C).

Bottom Line: D-Lc alone did not induce the secretion of IgA by CD40-activated naive B cells, which required further addition of IL-10.In the presence of IL-10, secretion of IgA2 by CD40-activated naive B cells could be detected only in response to D-Lc and was further enhanced by TGF-beta.Collectively, these results suggest that in addition to activating T cells in the extrafollicular areas of secondary lymphoid organs, human D-Lc also directly modulate T cell-dependent B cell growth and differentiation, by inducing the IgA isotype switch.

View Article: PubMed Central - PubMed

Affiliation: Schering-Plough, Laboratory for Immunological Research, Dardilly, France.

ABSTRACT
Within T cell-rich areas of secondary lymphoid organs, interdigitating dendritic cells recruit antigen-specific T cells that then induce B cells to secrete Igs. This study investigates the possible role(s) of dendritic cells in the regulation of human B cell responses. In the absence of exogenous cytokines, in vitro generated dendritic cells (referred to as Dendritic Langerhans cells, D-Lc) induced surface IgA expression on approximately 10% of CD40-activated naive sIgD+ B cells. In the presence of IL-10 and TGF-beta, a combination of cytokines previously identified for its capacity to induce IgA switch, D-Lc strongly potentiated the induction of sIgA on CD40-activated naive B cells from 5% to 40-50%. D-Lc alone did not induce the secretion of IgA by CD40-activated naive B cells, which required further addition of IL-10. Furthermore, D-Lc skewed towards the IgA isotype at the expense of IgG, the Ig production of CD40-activated naive B cells cultured in the presence of IL-10 and TGF-beta. Importantly, under these culture conditions, both IgA1 and IgA2 were detected. In the presence of IL-10, secretion of IgA2 by CD40-activated naive B cells could be detected only in response to D-Lc and was further enhanced by TGF-beta. Collectively, these results suggest that in addition to activating T cells in the extrafollicular areas of secondary lymphoid organs, human D-Lc also directly modulate T cell-dependent B cell growth and differentiation, by inducing the IgA isotype switch.

Show MeSH
Related in: MedlinePlus