Immune Cells Tactics: Divide and Conquer

Discovery could pave way to better vaccines

(RxWiki News) Scientists understand the big picture of how vaccines work in the body but not all the specifics at the cellular level. Now they have discovered one more piece of the puzzle.

When most cells divide, they produce identical "daughter" cells with all the same proteins in all the same ratios as their parent cells.

But one type of immune cell, the B cells that produce antibodies to fight infection, manage to produce diverse daughter cells.

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Scientists believe this ability helps vaccines to work since they trigger the production of those antibodies, but until now they didn't know how B cells managed this trick. Understanding this mechanism might help researchers produce more effective vaccines.

Dr. Steve Reiner and his student Burton Barnett at the Perelman School of Medicine at the University of Pennsylvania have recently figured out that the details of the relationship between B cells and another immune cell, called a T cell, which cues B cells to create those unlike daughter cells.

When an infection - or a vaccine that tricks the body into thinking it has an infection - enters the body, it activates the T cells, who realize a germ is in the body and that it needs to be eliminated.

B cells are like lone rangers - they circulate throughout the blood stream looking for a good fight. When an infection invades the body, B cells come to the rescue, but they can only win if they produce a variety of different types of daughter cells, including the antibodies that destroy the germs and quality-control cells that make those antibodies even better.

Unlike most cells, such as skin cells, that have life-long attachments with their own kind, free roaming B cells will hook up with a T cell when it's time to fight. These helper T cells attach to the B cells, causing the B cell to divide and produce daughter cells with different levels of proteins.

A different ratio of proteins creates a different type of daughter cell. Reiner and Barnett figured out what three proteins tell the B cell which type to create.

Once the B cells have a mechanism for producing different types of cells - the variations of these three proteins - they can produce armies of antibodies to fight off the infection.

The antibodies are specialized to fight whatever pathogen is in the body, so whatever antibody cells remain after the pathogen is gone will be available if that same pathogen returns.

Hence, the way a vaccine can trigger the body to be ready in case it encounters that disease in the future.

Now that scientists understand better how the B cells manage to create such different, specialized antibodies, they may be able to use this knowledge to create better vaccines.

"A better understanding of immunological memory will be important in making better, longer lasting vaccines," said Dr. Paul Offit, chief of the Division of Infectious Diseases and director of the Vaccine Education Center at the Children's Hospital of Philadelphia, in talking with DailyRx.

Offit is familiar with vaccine development from having invented the rotavirus vaccine now routinely given to children. "This paper sheds some light on the factors that contribute to B-cell responses that could impact vaccine design," he said.

This discovery might also help researchers understand how blood cells can turn into cancers like leukemia.

The Penn team's paper was published online in December in Science.

Review Date: 
December 23, 2011