Structure allows autoantigenic epitopes to induce autoimmune response.

2004 JUN 2 - (NewsRx.com & NewsRx.net) -- Structural availability influences the capacity of autoantigenic epitopes to induce a widespread lupus-like autoimmune response.

"A subset of lupus patients with severe nephritis and anti-nRNP reactivity produces autoantibodies primarily against two major epitopes of the nRNP A (also known as U1A) protein. These sequences span amino acids 44-56 (A3) and amino acids 103-115 (A6). These two epitopes represent structurally different regions of the protein, as both epitopes are located on the surface, but the A6 epitope is functionally masked in vivo by binding between nRNP A and the U1 RNA. Rabbits were immunized with either the A3 or A6 peptides constructed on a branching polylysine backbone," researchers in the United States report.

"Rabbits immunized with each of these peptides first developed antibodies directed against the peptide of immunization," stated Micah T. McClain and collaborators at the University of Oklahoma and the New Jersey Medical School. "With boosting, the immune response of rabbits immunized with the A3 peptide spread to other common antigenic regions of nRNP A. These regions of nRNP A bound by A3 immunized rabbits are very similar to common epitopes in human systemic lupus erythematosus. These A3 immunized rabbits also develop antibodies to common antigenic regions of nRNP 70K, nRNP C, Sm B/B' and Sm D1 proteins, as well as clinical symptoms of systemic lupus erythematosus such as leukopenia and renal insufficiency."

"On the other hand, ...