Abstract |
Mycoplasma arthritidis mitogen (MAM) is produced by an organism which can cause chronic proliferative arthritis in rodents. MAM possesses a typical superantigenic activity; it has the ability to activate a large panel of T cells which express specific V beta segments of the T-cell receptor. The presentation of MAM to T cells by antigen-presenting cells is mediated primarily through its binding to the major histocompatibility complex (MHC) class II E alpha chain in mice and the DR alpha chain in humans. However, MAM is much less active for human peripheral blood lymphocytes than for mouse splenocytes. It was suggested that a difference in MAM binding affinity between human and mouse class II molecules may account for their different MAM activities. To examine this possibility, we generated a panel of B-cell transfectants whose DR molecule is composed of either the DR alpha or the E alpha chain paired with a DR3 beta chain. The ability of these transfectants to present MAM to human peripheral T cells was analyzed. Our data show that transfectants expressing E alpha DR beta chimeric molecules have higher MAM-presenting activity than transfectants expressing wild-type DR alpha DR beta molecules, while the latter have higher activity in stimulating DR3-alloreactive T cells. Since both types of transfectants present MAM to T cells expressing the same T-cell receptor V beta gene families, the higher MAM-presenting activity of the E alpha transfectant is not due to its ability to interact with a different set of T cells. Furthermore, both the E alpha 1 and E alpha 2 domains contribute to this increased affinity for MAM binding. Taken together, our data suggest that there may be multiple MAM binding sites on the E alpha and DR alpha chains and residues unique to the E alpha chain may provide additional affinity for MAM.
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Authors | T Sawada, R Pergolizzi, K Ito, J Silver, C Atkin, B C Cole, M D Chang |
Journal | Infection and immunity
(Infect Immun)
Vol. 63
Issue 9
Pg. 3367-72
(Sep 1995)
ISSN: 0019-9567 [Print] United States |
PMID | 7642264
(Publication Type: Journal Article, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, P.H.S.)
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Chemical References |
- HLA-DR Antigens
- Superantigens
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Topics |
- Antigen Presentation
- Base Sequence
- Binding Sites
- Cell Line
- HLA-DR Antigens
(chemistry, metabolism)
- Humans
- Lymphocyte Activation
- Molecular Sequence Data
- Mycoplasma
(immunology)
- Superantigens
(metabolism)
- T-Lymphocytes
(immunology)
- Transfection
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