<i>Ortho</i>- and <i>meta</i>-monochlorinated biphenyls suppress humoral immunity and exert toxic effects on mouse liver cells

Widespread environmental contamination with polychlorinated biphenyls (PCBs) leads to serious health problems for humans and animals. Our main focus should be on studying the negative effects of exposure to medium- and highly chlorinated PCBs in the human body. There is limited information on the impact of low-chlorinated biphenyls containing 1-2 substituents per molecule on the functions of mammalian organs and systems. Under natural conditions, PCBs can undergo bacterial degradation; the resulting compounds belong to a group of secondary pollutants and are considered hazardous to the environment. Because of limited research, the question regarding the impact of mono-substituted chlorobiphenyl congeners, as well as the products of their biotransformation, remains open. In the presented work, the effects of <i>ortho</i>- and <i>meta</i>- substituted monochlorinated biphenyls on the functions of immune system cells and the morphofunctional state of the liver of mammals <i>in vivo</i> are revealed for the first time. PCB 1 and PCB 2 were found to suppress humoral immunity and induce a productive inflammatory response, as well as widespread protein dystrophy with necrotic foci in the liver. The products of a aerobic bacterial transformation of PCB 1 and PCB 2 were shown to not have a negative effect on the mammalian immune system but proved toxic to hepatocytes, although to a lesser extent than the original chlorobiphenyls.