Thimerosal Alters Dendritic Cell Response in Vitro

Mitch Kennedy, ND

Thimerosal, a methylmercury-based compound used for decades as a vaccine preservative, has previously been linked to neurotoxic effects. New research reveals that it may also affect the immune system by altering how dendritic cells respond to biochemical signals

Dendritic cells are influential primary actors in the immune system’s response to infectious invasion of the body. Once activated, a single dendritic cell can direct hundreds of T cells against an infectious agent. This ability, however, depends on the dendritic cell responding appropriately to signals.

Hypothesizing that dendritic cells might be sensitive targets, the researchers cultured bone marrow–derived dendritic cells from mice and assayed how both mature and immature cells responded to activation following treatment with thimerosal.

Exposure to thimerosal at concentrations as low as 20 ppb altered the time course of cell responses and prolonged the length of time that intracellular calcium levels remained elevated. One possible consequence of these sustained calcium levels is a change in the rate and timing of dendritic cells’ secretion of interleukin-6, a chemical that triggers further immune system action. Exposure to thimerosal at concentrations above 200 ppb caused immature dendritic cells to die.

Source: Goth et al: Uncoupling of ATP-mediated calcium signaling and dysregulated interleukin-6 secretion in dendritic cells by nanomolar thimerosal, Environ Health Perspect 114:1083-91, 2006.

Mitch Kennedy, ND, has a family practice in Avon, Connecticut, and is the first ND with clinical privileges at the University of Connecticut, a teaching hospital. Before graduating from Southwest College, Dr. Kennedy earned an international reputation as a leader in pollution prevention, showing industries around the world how preventing pollution saves money.