Effect low frequency noise exposure on BALB/c mice splenic lymphocytes

Vibroacoustic disease (VAD) occurs in workers exposed for more 10 yr to large pressure amplitude and low frequency (LPALF) noise (> or = 90dB, < or = 500 Hz). In its initial stages (2 yr exposure), VAD is associated with an increase in infections of the respiratory tract. The purpose of this study is to investigate whether exposure of mice to LPALF noise leads to immunological changes as expressed by the number of different lymphocyte subpopulations in the animals' spleen.

Flow cytometry analysis of spleen lymphocytes was performed in BALB/c mice that had been exposed to occupationally simulated LPALF noise (8 h x d(-1), 5 d x wk(-1)) for a total of 1272 h (approximately 8 mo). The following surface phenotypes of splenic lymphocytes were quantified: IgM, CD4, CD8. Quantification of splenic lymphocytes from non-exposed, age-matched, control BALB/c mice was also performed.

Noise-exposed BALB/c mice had decreased T cells, involving both helper (CD4+) and cytotoxic (CD8+) lymphocytes, and also of IgM+ B lymphocytes.

The data indicate that relatively short term exposure (3 mo) to LPALF noise induces a decrease in spleen lymphocytes in mice which is particularly significant (p < 0.003) in CD8+ T lymphocytes. The data suggest that exposure to LPALF noise causes changes in the immune system of mice. This is in agreement with previous human studies where VAD patients presented an enhancement in the number of circulating CD8+ lymphocytes.