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More MS news articles for July 2003

MHC class II peptide flanking residues of exogenous antigens influence recognition by autoreactive T cells

Autoimmun Rev. 2003 Jan;2(1):8-12
Conant SB, Swanborg RH.
Department of Immunology and Microbiology, Wayne State University School of Medicine, 48201, Detroit, MI, USA

Molecular mimicry between exogenous microbial antigens and self-epitopes has been proposed as a triggering mechanism for autoimmune diseases for many years.

We reported that a peptide from a protein specific to Chlamydia pneumoniae (Cpn0483) which shares a motif with the dominant encephalitogenic epitope of the self-antigen, rat myelin basic protein (rat68-86), elicits experimental autoimmune encephalomyelitis (EAE) in Lewis rats.

We recently observed that rat68-86 utilizes aspartic acid (D) and arginine (R) in the common motif as primary and secondary TCR contacts, respectively.

In contrast, the encephalitogenic activity of Cpn0483 is dependent on R and the C-terminal asparagine (N), which flanks the MHC class II-P9 anchor residue.

Thus, rat68-86 and Cpn0483 share a common motif, are encephalitogenic and are both restricted by MHC class II RT1.B(l).

T cells from rats immunized with the encephalitogenic Cpn0483 peptide proliferated to the priming peptide as well as to the non-encephalitogenic CpnN>A analog.

However, CpnN>A-primed T cells did not respond to the native Cpn0483 peptide.

We conclude that the MHC-flanking C-terminal asparagine residue markedly influences T cell recognition by the chlamydial peptide.