Preventing arthritis
This led to the search for a common sequence among the different HLA DRB1 alleles that were associated with RA. preventing arthritis Pain in liver. (top of section) The Shared Epitope Much of the heterogeneity of the MHC Class II molecules is conveyed by the three hypervariable regions in the b chain. Comparison of the amino acid sequences of the 14 DR4 alleles in these regions led to the identification, in the third hypervariable region, of a conserved amino acid sequence that consistently associated with the presence of RA. This sequence (positions 70-74) consists of glutamine (Q), lysine or arginine (K or R), arginine (R), alanine (A), and alanine (A) (slide). preventing arthritis Arthritis medicines. This conserved stretch of amino acids localized to the helical loop forms above the antigen binding groove of the DR4 molecule. Even more compelling was demonstration of the same amino acid sequence in Ashkenazi Jews with RA who were DR1, and not DR4, positive. These observations provided strong support for the concept of a shared epitope, encoded by the DR4 or DR1 B1 chains, that is believed to confer disease susceptibility and/or mediate disease severity. preventing arthritis Severe hip pain. The conserved QKRAA sequence could convey disease susceptibility by serving as a binding epitope for a specific arthritogenic peptide or it may provide a specific epitope for T cell receptor interaction. Some have suggested that the conserved sequence could itself serve as an immunogen (slide). Recent studies indicate that the DR4 shared epitope is not found with such high prevalence in Afro-Americans with RA, and it has been suggested that DR4 may be a marker for disease severity rather than disease susceptibility. This remains controversial. (top of section) MHC-T cell-Peptide Interaction The major function of MHC Class II molecules, such as DR4, is to present peptide antigen to CD4+ ("helper") T cells (slide). The CD4+ cell, upon recognition of the peptide antigen, becomes activated to initiate a host response. The finding that the structure of a Class II molecule can predispose a patient to the development of RA, therefore, strongly supports a role for CD4+ T cells in the pathogenesis of RA - at least, in the initiation of disease.
Preventing arthritis
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