A recently identified immune cell that directs other cells to fight infection plays a critical role in regulating the immune system in both health and disease, says a new study.
University of Pennsylvania School of Medicine researchers have discovered how a stimulatory molecule and a protein found on the membrane of another immune cell make T helper 17 cells multi-taskers of sorts.
Th17 cells protect the body against infection and cancer, but are also culprits in some autoimmune diseases and out-of-control, cancerous cell growth.
This new understanding that Th17 cells manage to play both sides of the fence suggests that targeting or inhibiting the involved protein pathways might be a new way to treat cancer, chronic infection, and some autoimmune diseases.
Previous studies have linked excessive amounts of Th17 cells in the body to such autoimmune diseases as multiple sclerosis, psoriasis, rheumatoid arthritis, and Crohn's disease.
Chrystal Paulos, Carl June colleagues have found that a protein called inducible costimulator (ICOS) is necessary for the growth and function of human Th17 cells, while CD28, a transmembrane protein on CD4 cells, stops the ICOS signal.
What's more, human Th17 stimulated with ICOS shrank human tumors implanted in a mouse model faster than those stimulated with CD28.
The new data on Th17 cells raises the possibility that the full inflammatory potential of human Th17 cells had not been fully reflected by previous lab studies.
The team also demonstrated that Th17 cells cannot only be expanded to large numbers, but could also be maintained by stimulating them with ICOS proteins.
The findings appeared in Science Translational Medicine.