CHAMPAIGN, Ill. -- Scientists have located -- and produced a vivid picture
of -- specific cells that contain receptors for a hormone-like substance
made by the immune system and associated with declines in growth-hormone
production in animals with bacterial infections.
The findings included two surprises and may help scientists understand how the immune system harnesses other physiological systems to regulate animal growth and disease. First, the receptors were found on cells in the pituitary gland, and, second, they were on somatotrope cells, which make growth hormone. Previous theory held that they were on corticotrope cells, makers of stress hormones.
The research, directed by Keith Kelley, a University of Illinois animal scientist and immunologist, led to a color snapshot of a direct link between the body's immune and endocrine systems. The work was featured on the cover and inside the September issue of the journal Endocrinology.
Specifically, researchers identified two types of receptors for interleukin-1 (IL-1), a molecule produced by the body's immune system during a bacterial infection, on the somatotrope cells in the pars anterior (outside sections) of the pituitary gland. The research, funded by the National Institutes of Health, was done using monoclonal antibodies as a stain to zero in on the morphology of cells in mice.
"This work shows us a marriage of the endocrine and immune systems," Kelley said. "These data give us a new set of glasses -- a new way of looking at the world that has always assumed that such interaction had to occur in the brain. The findings suggest that growth-hormone synthesizing cells in the pituitary also have the eyes that can sense the presence of disease-causing bacterium."
When a bacterium enters the body, it is taken in by macrophages, which are cells scattered throughout the body that ingest foreign cells. The bacterium causes the macrophages to produce IL-1, a message-carry
Contact: Jim E. Barlow, Life Sciences Editor
University of Illinois at Urbana-Champaign