Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


UC Davis study with mice links thimerosal with immune system dysfunction


A team of cell biologists, toxicologists and molecular bioscientists at UC Davis has published a study connecting thimerosal with disruptions in antigen-presenting cells known as dendritic cells obtained from mice. The study provides the first evidence that dendritic cells show unprecedented sensitivity to thimerosal, resulting in fundamental changes in the immune system’s ability to respond to external factors. The study was published online today and will be available in the July print edition of Environmental Health Perspectives, the peer-reviewed scientific publication of the National Institute of Environmental Health Sciences.

"This is the first time that thimerosal has been shown to selectively alter the normal functions of dendritic cells," said Isaac Pessah, a toxicologist with the UC Davis School of Veterinary Medicine, director of the Children’s Center for Environmental Health and Disease Prevention and senior author of the study. "Dendritic cells play pivotal roles in overcoming viral and bacterial invaders by coordinating the immune system’s overall combat response." One dendritic cell can activate as many as 300 T-cells – white blood cells that help find and kill external agents that attack the immune system – making them the most effective immune system activators.

The study shows how intricate connections between calcium channels in dendritic cells change when exposed to thimerosal.

"The slightest fluctuation in how calcium channels ’communicate’ can alter the growth, maturation and activation of dendritic cells," explained Pessah. "Thimerosal dramatically alters how two key calcium channels, code-named RyR1 and IP3R1, found in dendritic cells function as a team by ’garbling’ the normal signaling system between them."

When thimerosal, at a concentration as low as 20 parts per billion, alters the fidelity of normal calcium signals, dendritic cells show abnormal secretion of IL-6 cytokine – a potent chemical signal that initiates inflammatory responses. Higher concentrations – 200 parts per billion – causes programmed death of dendritic cells, preventing them from maturing and doing their primary job of activating T-cells. Without proper feedback to guide its response, a normal dendritic cell can quickly become "a rogue, producing misinformation that could activate aberrant and harmful immune responses," Pessah explained. "Even one rogue dendritic cell can activate many inappropriate immune responses."

The research team conducted the study on cells cultured from a strain of mouse not particularly susceptible to immune dysregulation. Using fluorescent stains and powerful microscopes to study both immature and mature dendritic cells from bone marrow cultured under normal physiological conditions, the researchers discovered that extremely small levels of thimerosal interfere significantly with calcium channel function after just a few minutes of exposure. They also observed that immature dendritic cells are particularly sensitive to thimerosal.

Thimerosal is a cheap and effective mercury-based preservative. Its potential effects on embryonic neuron development led to its removal from many pediatric vaccines. However, it is still used in influenza, diphtheria and tetanus vaccines, blood products and many over-the-counter pharmaceuticals. The concentrations of thimerosal used by the UC Davis researchers were comparable to those attained in childhood vaccinations containing the preservative.

Researchers and parents have previously proposed links between childhood vaccines and autism, a neurodevelopmental disorder that affects language skills and social interactions. The UC Davis study indicates that in addition to being a direct neurotoxicant, thimerosal may also be an immunotoxicant, leaving the immune system vulnerable to microbes and other external influences.

"Our findings do not directly implicate thimerosal as a single causative agent for triggering neurodevelopmental disorders such as autism," Pessah said. "There is growing evidence that autism is several disorders that we now refer to as just one. There is also growing evidence that some children with autism have unique immune cell composition and responses to antigens. The results of our work provide a framework to test the hypothesis that the genetic background of some individuals may render them especially susceptible to thimerosal."

Other experts also advise drawing no final conclusions regarding thimerosal and autism based on these outcomes.

"These findings should be interpreted cautiously. Although they suggest that thimerosal may affect dendritic cell function, the pathophysiological consequences of thimerosal remain unclear," said David A. Schwartz, a physician and director of the National Institute of Environmental Health Sciences.

Since cell functions can differ across organisms, Pessah will next study dendritic cells isolated from the blood of children with and without autism to confirm if the intercellular changes are the same in humans. The initial mouse study was funded by the National Institute of Environmental Health Sciences and the UC Davis M.I.N.D. Institute. Joining Pessah on the scientific team were molecular bioscientists Samuel R. Goth, Ruth A. Chu and Gennady Cherednichenko and pathologist Jeffrey P. Gregg.

Karen Finney | EurekAlert!
Further information:

More articles from Life Sciences:

nachricht Bioluminescent sensor causes brain cells to glow in the dark
28.10.2016 | Vanderbilt University

nachricht Activation of 2 genes linked to development of atherosclerosis
28.10.2016 | Brigham and Women's Hospital

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Novel light sources made of 2D materials

Physicists from the University of Würzburg have designed a light source that emits photon pairs. Two-photon sources are particularly well suited for tap-proof data encryption. The experiment's key ingredients: a semiconductor crystal and some sticky tape.

So-called monolayers are at the heart of the research activities. These "super materials" (as the prestigious science magazine "Nature" puts it) have been...

Im Focus: Etching Microstructures with Lasers

Ultrafast lasers have introduced new possibilities in engraving ultrafine structures, and scientists are now also investigating how to use them to etch microstructures into thin glass. There are possible applications in analytics (lab on a chip) and especially in electronics and the consumer sector, where great interest has been shown.

This new method was born of a surprising phenomenon: irradiating glass in a particular way with an ultrafast laser has the effect of making the glass up to a...

Im Focus: Light-driven atomic rotations excite magnetic waves

Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion

Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Steering a fusion plasma toward stability

28.10.2016 | Power and Electrical Engineering

Bioluminescent sensor causes brain cells to glow in the dark

28.10.2016 | Life Sciences

Activation of 2 genes linked to development of atherosclerosis

28.10.2016 | Life Sciences

More VideoLinks >>>