( tem's physical behavior at the molecula...)Immune system has evolved to prevent autoimmune disease

Generating antibodies is one of the primary functions of the immune system. Antibodies are protein molecules that are made by B cells. Each antibody has a chemical signature that allows it to bind only with a particular sequence of amino acids.

"In our study, we first sought to understand the evolutionary rules that govern the way the immune system responds to an infection," Deem said. "With that framework in place, we identified a biologically-plausible strategy that would allow the immune system to react more quickly and with more effective antibodies. Our analysis revealed that such a system would be about 1,000 times more likely to produce antibodies that attack healthy tissues."

Antibodies that bind with something other than the antigen they evolved to attack are called cross-reactive, and some researchers believe cross-reactivity causes some autoimmune diseases.

For example, some scientists have found a correlation between chronic infection and an increased probability of autoimmune disease, but the strength and significance of the correlation is controversial. Rice's model suggests that a correlation does exist, but that the length of the infection prior to onset of autoimmune disease is highly variable.

"People have been looking for a clear, significant correlation in time, but a long distribution of onset times would lead to weaker statistical correlations, particularly in those cases where the infection persisted the longest," said Deem. "Searching for this distribution in health and medical statistics could shed light on this immunological puzzle and settle the scientific controversy."

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Source:Rice University