Immunity system complexity: B cells produce antibodies (Introduction)

by David Turell , Monday, August 24, 2020, 21:11 (1551 days ago) @ David Turell

They are the key source for new antibodies, and respond best to flexible antigens:

https://medicalxpress.com/news/2020-08-flexible-immune-finely-tuned-antibodies.html

"'Long-lasting immunity is an important challenge for the immune system—antibodies have to bind like glue to foreign threats, such as viruses but avoid any of the body's own molecules as this can lead to autoimmunity," says Dr. Deborah Burnett, co-first author of the paper.

"At a sub-microscopic level, some molecules bend and move more than others—some are more rigid, while others are flexible. The same is true for molecules on viruses, for example, the spike protein on the SARS-CoV-2 virus that causes COVID-19 is highly flexible to adopt multiple different shapes.

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"'Using an artificial pair of foreign and self-molecules that are very similar, we created different versions of the same antigen, altering one connection that made it either more rigid or more flexible," says Dr. Schofield. The researchers then investigated how the immune system of mice generated antibodies to the different molecules.

"The researchers discovered that when the foreign antigen was more flexible, the germinal center could employ a greater number of evolution strategies to make antibodies that bound foreign but not self-molecules.

"'Our results showed that the antibodies initially bonded to both the rigid self and flexible foreign antigens in the same way, unable to tell them apart. What surprised us was that, after only a few weeks, when the foreign antigen was flexible, the antibodies were able to specifically mutate to become 67 times more selective for foreign antigens, and 19 times less selective for self," says Dr. Burnett. "The antibodies generated against rigid foreign antigens were more likely to have autoimmune properties.'" (my bold)

Comment: It is important that B cells make antibodies that don't attack their own body's cells. The design in this system minimizes that mistake.