Styrene Inhalation and Immune Function in Mice

Abstract

Short-term inhalation studies were conducted to evaluate the potential effects of styrene on the immune system. Female B6C3F1 mice were exposed by inhalation to 0, 125, 250, or 500 ppm styrene, 6 h/day for 14 consecutive days. Thymus and spleen weights in styrene-exposed mice were decreased in the high-dose animals, and a marked decrease in spleen cellularity occurred in all chemically treated groups. Cytometric analysis of spleen cells revealed a slight increase in the percentage of B cells and a decrease in the absolute number of CD4′ cells. This latter change was responsible for a shift in the CD4/CD8 ratio observed in the high dose group. Corresponding increases in the prolifer-ative response to the B-lymphocyte mitogen lipopolysaccharide as well as an increase in the primary antibody response to sheep erythrocytes were observed. Cell-mediated immunity was unaffected by styrene inhalation as demonstrated by normal cytotoxic T-lympho-cyte and mixed leukocyte responses. Changes in spleen cellularity were not reflected at the level of the stem cell, as bone marrow cellularity was unaffected by styrene treatment. Styrene slightly suppressed spleen natural killer (NK) cell activity without affecting lung NK cell activity. These studies indicate that the primary immune effect of styrene is splenic hypocellularity. Although an imbalance in the B and T spleen lymphocyte sub-populations and a decrease in spleen NK cell activity were observed, the magnitudes of these effects were minimal.