Differences in basal and induced DNA single-strand breaks between human peripheral monocytes and lymphocytes

Area of Science:

• Cellular and Molecular Biology
• Genotoxicology
• Immunology

Background:

• Peripheral mononuclear leukocytes (PML) are crucial for immune surveillance and biomonitoring.
• Understanding differential susceptibility to DNA damage in leukocyte subsets is vital for accurate genotoxicity assessment.
• Oxidative stress is implicated in various diseases and can induce DNA single-strand breaks (SSB).

Purpose of the Study:

• To compare the susceptibility of peripheral monocytes and lymphocytes to oxidant-induced DNA single-strand breaks (SSB).
• To investigate basal and hydrogen peroxide (H2O2)-induced SSB rates in isolated lymphocyte and monocyte populations.
• To assess the implications of differential DNA damage rates for biomonitoring and genotoxicity testing.

Main Methods:

• Alkaline single-cell gel electrophoresis (SCGE) assay used to quantify DNA SSB.
• Peripheral mononuclear leukocytes (PML) were fractionated into lymphocyte-enriched and monocyte-enriched populations.
• Cells were incubated in vitro with varying concentrations of H2O2 at 4°C to minimize DNA repair.

Main Results:

• Lymphocytes exhibited a 2.9-fold higher basal rate of SSB compared to monocytes.
• Lymphocytes showed an 11.3-fold greater rate of H2O2-induced SSB (10 µM) compared to monocytes.
• A significant linear correlation was observed between lymphocyte percentage and both basal and induced SSB rates.

Conclusions:

• Marked differences exist in basal and oxidant-induced SSB susceptibility between lymphocytes and monocytes.
• These findings suggest distinct antioxidant capacities between lymphocytes and monocytes.
• Cellular composition of PML samples must be considered in biomonitoring and genotoxicity assessments.