# Ortho- and Meta-monochlorinated Biphenyls Suppress Humoral Immunity and Exert Toxic Effects on Mouse Liver Cells

## TL;DR

This study shows that certain low-chlorinated biphenyls suppress immunity and harm liver cells in mice.

## Contribution

The first in vivo analysis of the effects of ortho- and meta-monochlorinated biphenyls on mammalian immunity and liver function.

## Key findings

- PCB 1 and PCB 2 suppressed humoral immunity and caused liver protein dystrophy with necrotic foci.
- Biotransformation products of PCB 1 and PCB 2 were less toxic to the immune system but still harmful to hepatocytes.
- Low-chlorinated biphenyls have significant negative effects on mammalian health despite limited prior research.

## Abstract

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 ortho- and
meta- substituted monochlorinated biphenyls on the functions
of immune system cells and the morphofunctional state of the liver of mammals
in vivo 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.