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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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Effects on B cell responses are strictly due to D-Lc. (A) Day  0, sorting of CD1a+ dendritic cells. (B) Day 7, induction of sIgA by  CD1a+-sorted dendritic cells. (C) Day 14, CD1a+-sorted dendritic cells  potentiate cytokine-induced IgA secretion. After 12 d maturation of  CD34+ hematopoietic progenitors into dendritic cells, D-Lc were sorted  on the basis of CD1a expression (A). 5 × 104/ml sIgD+ B lymphocytes  were cultured in a final volume of 1 ml in the absence or presence of 5 ×  104/ml unseparated or sorted CD1a+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. Surface IgA on B cells was analyzed after 7 d  culture with IL-10 and TGF-β (B) and IgA secretion was measured at day  14 (C) as previously described.
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Figure 7: Effects on B cell responses are strictly due to D-Lc. (A) Day 0, sorting of CD1a+ dendritic cells. (B) Day 7, induction of sIgA by CD1a+-sorted dendritic cells. (C) Day 14, CD1a+-sorted dendritic cells potentiate cytokine-induced IgA secretion. After 12 d maturation of CD34+ hematopoietic progenitors into dendritic cells, D-Lc were sorted on the basis of CD1a expression (A). 5 × 104/ml sIgD+ B lymphocytes were cultured in a final volume of 1 ml in the absence or presence of 5 × 104/ml unseparated or sorted CD1a+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. Surface IgA on B cells was analyzed after 7 d culture with IL-10 and TGF-β (B) and IgA secretion was measured at day 14 (C) as previously described.

Mentions: Dendritic cells generated in vitro by culturing hematopoietic progenitors for 12 d in GM-CSF, TNF-α, and SCF contain between 50–90% of CD1a+ cells. To exclude the contribution of nondendritic cells, dendritic cells were sorted on the basis of CD1a expression. As shown in Fig. 7 A, purity of CD1a-sorted dendritic cells reached 95% (ranging from 95 to 97%, n = 3). CD1a-sorted Dendritic cells were capable to induce comparable levels of sIgA on CD40-activated sIgD+ B cells after 7 d of coculture in the presence of IL-10 and TGF-β than those obtained with unseparated D-Lc (30.1 versus 35.6%) (results obtained with CD1asorted Dendritic cells: mean 29.2 ± 0.8%, n = 3) (Fig. 7 B). In addition, as observed with unseparated D-Lc, CD1asorted Dendritic cells were able to potentiate IL-10-induced IgA secretion by CD40-activated sIgD+ B cells (Fig. 7 C) that was further increased in the presence of TGF-β.


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)

Effects on B cell responses are strictly due to D-Lc. (A) Day  0, sorting of CD1a+ dendritic cells. (B) Day 7, induction of sIgA by  CD1a+-sorted dendritic cells. (C) Day 14, CD1a+-sorted dendritic cells  potentiate cytokine-induced IgA secretion. After 12 d maturation of  CD34+ hematopoietic progenitors into dendritic cells, D-Lc were sorted  on the basis of CD1a expression (A). 5 × 104/ml sIgD+ B lymphocytes  were cultured in a final volume of 1 ml in the absence or presence of 5 ×  104/ml unseparated or sorted CD1a+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. Surface IgA on B cells was analyzed after 7 d  culture with IL-10 and TGF-β (B) and IgA secretion was measured at day  14 (C) as previously described.
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Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2196343&req=5

Figure 7: Effects on B cell responses are strictly due to D-Lc. (A) Day 0, sorting of CD1a+ dendritic cells. (B) Day 7, induction of sIgA by CD1a+-sorted dendritic cells. (C) Day 14, CD1a+-sorted dendritic cells potentiate cytokine-induced IgA secretion. After 12 d maturation of CD34+ hematopoietic progenitors into dendritic cells, D-Lc were sorted on the basis of CD1a expression (A). 5 × 104/ml sIgD+ B lymphocytes were cultured in a final volume of 1 ml in the absence or presence of 5 × 104/ml unseparated or sorted CD1a+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. Surface IgA on B cells was analyzed after 7 d culture with IL-10 and TGF-β (B) and IgA secretion was measured at day 14 (C) as previously described.
Mentions: Dendritic cells generated in vitro by culturing hematopoietic progenitors for 12 d in GM-CSF, TNF-α, and SCF contain between 50–90% of CD1a+ cells. To exclude the contribution of nondendritic cells, dendritic cells were sorted on the basis of CD1a expression. As shown in Fig. 7 A, purity of CD1a-sorted dendritic cells reached 95% (ranging from 95 to 97%, n = 3). CD1a-sorted Dendritic cells were capable to induce comparable levels of sIgA on CD40-activated sIgD+ B cells after 7 d of coculture in the presence of IL-10 and TGF-β than those obtained with unseparated D-Lc (30.1 versus 35.6%) (results obtained with CD1asorted Dendritic cells: mean 29.2 ± 0.8%, n = 3) (Fig. 7 B). In addition, as observed with unseparated D-Lc, CD1asorted Dendritic cells were able to potentiate IL-10-induced IgA secretion by CD40-activated sIgD+ B cells (Fig. 7 C) that was further increased in the presence of TGF-β.

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