Effect of inhaled industrial chemicals on systemic and local immune response

Using immunotoxic functional tests, namely IgM response to sheep red blood cells (SRBCs) and interferon-gamma (IFN-gamma) production, this study simultaneously evaluated the effects of inhaled chloroform (10, 20, and 50 ppm), carbon tetrachloride (100, 200, and 300 ppm), 1,1-dichloroethylene (5, 10, and 15 ppm), and styrene (100, 200, and 300 ppm) on the systemic (spleen) and local (lung-associated lymph nodes) immune response. At least one concentration of all the chemicals studied provoked a statistically significant increase in IgM response in the lymph nodes compared with the controls, as expressed by the number of plaque-forming cells (PFCs), whereas only the highest concentration of 1,1-dichloroethylene provoked an increase in the number of PFCs statistically different from the controls in the case of the spleens. The release of IFN-gamma in the lymph node cell cultures of the exposed mice exceeded that of the controls by more than 600%, whereas the release of IFN-gamma in the spleen cell cultures of the exposed mice was moderately different from the controls. It would appear from these results that the lung-associated lymph nodes are sensitive targets for chemical inhalation and that the results of systemic tests in the spleen may not mirror local immune response dysfunction. For risk assessment of inhaled chemicals, it is therefore important to take the local immunotoxic effects into consideration, in particular immunostimulation which may be involved in the rise in allergic diseases in industrialised countries.