Alterations in the pulmonary and systemic immune response in rats exposed to coal fly ash.

The effect of intratracheally injected fly ash on the development of pulmonary and systemic immunity was studied in rats. Following intratracheal and intraperitoneal immunisation with sheep red blood cells (SRBC) there was an appearance of antibody forming cells (AFC) in lung associated lymph nodes (LALN) of animals exposed to either fly ash or physiological saline. Enumeration of AFC in LALN after immunisation by either of the routes, revealed a reduction in the number of AFC in LALN of fly ash exposed rats in comparison to saline exposed animals. The reduction in the number of AFC was more pronounced after exposure of Cd-coated fly ash. The AFC appeared in the spleen only after immunisation through intraperitoneal route and the number of AFC in spleen of the fly ash and saline exposed group of animals did not show any significant difference. These results demonstrate that fly ash burden of lungs results in an impairment of the local immune response of the lungs without an associated effect on the systemic immunity.