[Metallothioneins as stressor proteins modulating the immune response]

Matallothioneins are a group of cellular proteins whose synthesis increases considerably in conditions of stressful reactions to harmful environmental factors, especially to heavy metals. They are considered to be proteins of intracellular activity whose specific effect on the metal-dependent enzymes is revealed within the cells, as well as proteins which regulate the transcription process. Metallothioneins released from cells to extracellular fluids, for example due to the damage of membrane, may disclose non-specific effect which usually does not occur. In such conditions, metallothioneins may also affect other cells of tissues and organs placed far away from targets of heavy metal. They also play an important role in the regulation of normal vital functions of the cells in the immune system. In numerous cases, because of their unique chemical structure and biological properties, metallothioneins perform the function of immunomodulators. In the majority of cases, the modulatory effect is favourable for the body as a whole. However, in some cases, this effect is negative, for example it hinders the removal of potentially neoplastic cells from the body.