Our immune system is our main line of protection from foreign pathogens and our own damaged cells. Although we often talk of the immune system as if it were one thing, it is really a complex, interconnected organization that includes many different types of cells, each with its own specialized activities and roles.


At Penn, investigators are studying the immune system at multiple levels, from basic  discovery to developing patient therapeutics. And while the general organization of the system is well known, investigators are still uncovering previously unknown functions. For example, David Artis, PhD, recently reported that a specialized type of lymphocyte, which was known to function during fetal development, also plays a critical role in protecting barrier tissues, such as skin, gut, and lung, in adult mice. Read more.


Other investigators are studying the ins and outs of how the immune system prevents infections, or controls them when they do occur. In one such study, E. John Wherry, PhD, Director of the Institute for Immunology, learned why immune cells ultimately lose a long battle with chronic infections such as hepatitis C or HIV. Read more.


Carl June, MD, and colleagues have developed a way to harvest and grow patient immune cells called T lymphocytes. They have learned how to modify the cells so that when they put them back in patients with cancer, the modified immune cells attack and kill the disease. The approach is still in clinical testing but has shown promising early results. Read more.


Every general knows the wisdom of defense in depth: multiple layers of protection to fend off and stop attackers.  Yet the idea originated not with military strategists but with nature, as humans and other organisms evolved a sophisticated and powerful multilayered immune system to keep out harmful microbial invaders and to destroy them if they get too far. 

The oldest part of the human immune system is called the complement system, or simply "complement,” so named because it enhances or "complements" the other more complex layers that evolved later. It's the first responder of the immune system, the early warning system that summons the rest of the body's defenses into action. Yet much of its function and how it interacts with the rest of the immune system has remained a mystery.  John Lambris, Ph.D.,the Dr. Ralph and Sallie Weaver Professor of Research Medicine, is illuminating the workings of complement, finding that its role actually extends far beyond merely helping our immune responses. Not only is it involved in the body's growth and development, but when it goes awry, complement can even hurt instead of help. Read more.

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