Changes in delayed hypersensitivity reaction in mice exposed to O3.

Area of Science:

• Environmental toxicology
• Immunology
• Respiratory health

Background:

• Ozone (O3) is a major air pollutant with known respiratory effects.
• The impact of ozone on immune function, particularly cell-mediated immunity, requires further elucidation.

Purpose of the Study:

• To investigate the effect of controlled ozone exposure on the delayed hypersensitivity (DH) immune response in BALB/c mice.
• To determine the impact of ozone on lymphocyte populations in the thymus and blood.

Main Methods:

• BALB/c mice were exposed to 0.8 ppm ozone for 1, 3, 7, and 14 days.
• The delayed hypersensitivity (DH) reaction to sheep red blood cells (SRBC) was measured.
• Lymphocyte counts and percentages (T and B cells) in thymus and blood were analyzed.

Main Results:

• Ozone exposure significantly suppressed the DH reaction, with maximum suppression observed at 7 days.
• A notable decrease in lymphocyte numbers was found in the thymus and blood of ozone-exposed mice.
• The proportion of T and B lymphocytes in the blood remained unchanged, suggesting a specific effect on T lymphocytes involved in DH.

Conclusions:

• Ozone exposure at 0.8 ppm impairs cell-mediated immunity in mice.
• The observed suppression of the DH reaction is associated with a reduction in T lymphocytes.
• These findings highlight the immunotoxic potential of ozone and its implications for immune defense.