Immunomodulation of Host as a Predictive Bio-Indicator of Toxicity in the Mammalian System

Abstract

Immune system is complex in nature, consisting of multi organ involvement in its activity. It is one of the most sensitive systems in the body. Any foreign material i.e. chemicals, drugs and micro-organisms, if enters in the body, may produce alteration in the function of the immune system. Only recently information has been generated that many environmental chemicals and drugs can produce modulation of the immune system in even low doses of exposure and for a short period. Some chemicals in low doses produce severe immunotoxicity well before producing any sign of overt toxicity to the other system. This can be only predicted by using immunotoxicological tests. The chemicals that enhance the immune response may predispose the host to auto-immune disease or lymphoreticular disorders resulting in allergic or hypersensitivity reactions. On the other hand, the chemicals that suppress immunity may sufficiently disrupt the immunoregulatory network, resulting in increased susceptibility to infection or to develop cancer.

In the recent past toxicological assessments were done by using lethal dose (50%) evaluation, use of biochemical and pathological examination of different organs, which gives information only about the cell number or degree of cellularity. The early effect of chemicals on the cell function may be missing in that type of study. Currently, the inclusion of immunological assessment parameters in toxicity evaluation of chemicals have made it possible to test the toxicity at the cellular level.

It has been well known that many of the environmental chemicals at very low doses can modulate immune system without producing any clinical sign or symptoms of the disease or disorders. It is of importance that assessment of  immunomodulation can be used as a sensitive bio-indicator for predicting the toxicity caused by environmental chemicals, since immunotoxicitv can be determined with much smaller dosages of chemicals than is needed for toxicity evaluation of chemicals using animals.