When the nasty looking guy behind you in your morning lecture sneezes violently, what keeps you from coming down with the same cold? The immune system, you may reflexively answer in quick fashion, fights off infection. Well sure, but how does your body grab on to invading particles and start its immune response?
The dendritic cell, named for the Greek term for "tree," plays a key role. Dr. Ralph Steinman first discovered the dendritic cell's key role in the immune system and was awarded the Nobel prize just two weeks ago. This particular Nobel prize made international headlines as Dr. Steinmann sadly passed away from pancreatic cancer just three days before the announcement, despite prolonging his life with therapy based upon his very own immunologic research.
Before scientists gained an understanding of dendritic cells, they knew about different types of white blood cells that fight infection. They knew there were B cells to make antibodies which grab onto infectious particles. They knew there were T cells to help coordinate the response and kill off infected cells. They knew B and T cells coordinated their complex and beautiful actions in lymph nodes around the body. But they did not fully appreciate how the body goes about finding which little invading bits may be scattered throughout the trillions of cells in the human body. Imagine B and T cells as master chefs on Food Network's "Iron Chef" who have no clue how to drive a car or where the nearest grocery store is. With the right starting ingredients, B and T cells can work very quickly to fight infection with excellent skill. The dendritic cell is a professional food shopper.
When the feverish nasty guy in lecture sneezes on you, little droplets carry virus particles to your nose. The lining in your nose lacks some of the thick protective layers your skin features, so the virus gets underneath the lining fairly easily. Thankfully, the immune system is primed and waiting, featuring specialized antibodies, white blood cells and, of course, dendritic cells. Sliding along through barrier tissues like an experienced shopper through the aisles of Harris Teeter, the dendritic cells pick up and sample each item. Afterward, they drive home to the nearest lymph node where teams of different types of B and T white blood cells reside, like chefs in the kitchen waiting for ingredients. If the dendritic cell presents the right item, Iron Chef Lymph Node commences and an immune system response takes off, helping your body to mount its defenses quickly against the newly discovered invader.
But it turns out the dendritic cell is more than just a professional molecular shopper. The dendritic cell can help guide what type of response the B and T cells generate with the morsels it provides. It can also produce chemicals which aid the immune response at the site where it first encounters an invader. Finally, the dendritic cell can remind the rest of the immune system to pay attention to an infection which has lingered long enough that the body would otherwise ignore it.
So wash your hands and cover your sneezes with the inside of your elbow. But do not despair when smothered with a classmate's wet sneeze. You have a cellular culinary force fighting the good fight every day, with the powerful and flexible dendritic cell always shopping for the next meal.
Tom Mendel is a University Medical student. He can be reached at t.mendel@cavalierdaily.com
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