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Paracrine transfer of mouse mammary tumor virus superantigen.

Delcourt M, Thibodeau J, Denis F, Sekaly RP - J. Exp. Med. (1997)

Bottom Line: We show that this transfer activity is paracrine but does not require cell-to-cell contact.Transfer can occur both from class II+ and class II+ cells, indicating that MHC class II does not sequester vSAG7.Finally, competition experiments using bacterial toxins with well defined binding sites showed that the transferred vSAG7 fragment binds to the alpha 1 domain of HLA-DR.

View Article: PubMed Central - PubMed

Affiliation: Laboratoire d'Immunologie Institut de Recherches Cliniques de Montréal, Canada.

ABSTRACT
Transfer of vSAG7, the endogenous superantigen encoded in the Mtv7 locus, from MHC class II to MHC class II+ cells has been suggested to occur both in vivo and in vitro. This transfer usually leads to the activation and deletion of T cells expressing responsive V beta s. However, there is no direct molecular evidence for such a transfer. We have developed an in vitro system which confirms this property of vSAGs. vSAG7 was transfected into a class II murine fibroblastic line. Coculture of these cells with class II+ cells and murine T cell hybridomas expressing the specific V beta s led to high levels of IL-2 production which was specifically inhibited by vSAG7- and MHC class II-specific mAbs. Moreover, injection of vSAG7+ class II+ cells in mice led to expansion of V beta 6+ CD4+ cells. We show that this transfer activity is paracrine but does not require cell-to-cell contact. Indeed, vSAG7 was transferred across semi-permeable membranes. Transfer can occur both from class II+ and class II+ cells, indicating that MHC class II does not sequester vSAG7. Finally, competition experiments using bacterial toxins with well defined binding sites showed that the transferred vSAG7 fragment binds to the alpha 1 domain of HLA-DR.

Show MeSH
vSAG7 can be transferred despite the presence of MHC class  II molecules on donor cells. Various concentrations of DAP DR1 vSAG7  cells clone 3B2 or 3A5 were disposed in the upper compartment. The experiment was then performed as described in Fig. 6 b.
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Figure 7: vSAG7 can be transferred despite the presence of MHC class II molecules on donor cells. Various concentrations of DAP DR1 vSAG7 cells clone 3B2 or 3A5 were disposed in the upper compartment. The experiment was then performed as described in Fig. 6 b.

Mentions: Similar experiments were performed using DAP DR1 vSAG7 cells in the upper compartment. Our results (Fig. 7) show that the transferred fragment of vSAG7 crosses the membrane and stimulates efficiently Vβ12+ PBMCs. These results were obtained using two different DAP DR1 vSAG7 clones, 3B2 and 3A5. The results obtained using DAP vSAG7 or DAP DR1 vSAG7 (Figs. 6 b and 7) were very similar: in both cases a small and comparable proportion of vSAG molecules were able to cross the membrane and stimulate PBMCs. These results indicate that the MHC class II molecules expressed by DAP DR1 cells are not interfering with the transfer of vSAG7 molecules.


Paracrine transfer of mouse mammary tumor virus superantigen.

Delcourt M, Thibodeau J, Denis F, Sekaly RP - J. Exp. Med. (1997)

vSAG7 can be transferred despite the presence of MHC class  II molecules on donor cells. Various concentrations of DAP DR1 vSAG7  cells clone 3B2 or 3A5 were disposed in the upper compartment. The experiment was then performed as described in Fig. 6 b.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2196028&req=5

Figure 7: vSAG7 can be transferred despite the presence of MHC class II molecules on donor cells. Various concentrations of DAP DR1 vSAG7 cells clone 3B2 or 3A5 were disposed in the upper compartment. The experiment was then performed as described in Fig. 6 b.
Mentions: Similar experiments were performed using DAP DR1 vSAG7 cells in the upper compartment. Our results (Fig. 7) show that the transferred fragment of vSAG7 crosses the membrane and stimulates efficiently Vβ12+ PBMCs. These results were obtained using two different DAP DR1 vSAG7 clones, 3B2 and 3A5. The results obtained using DAP vSAG7 or DAP DR1 vSAG7 (Figs. 6 b and 7) were very similar: in both cases a small and comparable proportion of vSAG molecules were able to cross the membrane and stimulate PBMCs. These results indicate that the MHC class II molecules expressed by DAP DR1 cells are not interfering with the transfer of vSAG7 molecules.

Bottom Line: We show that this transfer activity is paracrine but does not require cell-to-cell contact.Transfer can occur both from class II+ and class II+ cells, indicating that MHC class II does not sequester vSAG7.Finally, competition experiments using bacterial toxins with well defined binding sites showed that the transferred vSAG7 fragment binds to the alpha 1 domain of HLA-DR.

View Article: PubMed Central - PubMed

Affiliation: Laboratoire d'Immunologie Institut de Recherches Cliniques de Montréal, Canada.

ABSTRACT
Transfer of vSAG7, the endogenous superantigen encoded in the Mtv7 locus, from MHC class II to MHC class II+ cells has been suggested to occur both in vivo and in vitro. This transfer usually leads to the activation and deletion of T cells expressing responsive V beta s. However, there is no direct molecular evidence for such a transfer. We have developed an in vitro system which confirms this property of vSAGs. vSAG7 was transfected into a class II murine fibroblastic line. Coculture of these cells with class II+ cells and murine T cell hybridomas expressing the specific V beta s led to high levels of IL-2 production which was specifically inhibited by vSAG7- and MHC class II-specific mAbs. Moreover, injection of vSAG7+ class II+ cells in mice led to expansion of V beta 6+ CD4+ cells. We show that this transfer activity is paracrine but does not require cell-to-cell contact. Indeed, vSAG7 was transferred across semi-permeable membranes. Transfer can occur both from class II+ and class II+ cells, indicating that MHC class II does not sequester vSAG7. Finally, competition experiments using bacterial toxins with well defined binding sites showed that the transferred vSAG7 fragment binds to the alpha 1 domain of HLA-DR.

Show MeSH