Shashi Dogra

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.

In vivo effect of fly ash on surface receptors of mice peritoneal macrophages

Abstract Functional activity of macrophages was studied in mice upto 15 days after intraperitoneal injection of 2.5 and 5.0 mg of fly ash using in vitro parameters. Fly ash did not cause any variation in the type of cellular response. The total cell number decreased significantly by 4 days after fly ash treatment but recovered subsequently. The decrease was dose dependent. Fly ash also caused a 50% depression in the FC receptor mediated phagocytosis of IgG coated sheep erythrocytes (SRBC) by macrophages at 2 days of dust treatment. However, the recovery began earlier with 2.5 mg fly ash than with 5.0 mg fly ash. These changes were not associated with any marked changes in esterase activity of macrophages following phagocytosis of fly ash.

Pulmonary clearance of Candida albicans : Effect of exposure to native and metal-coated fly ash

The viability of Candida albicans was tested at various intervals in the lungs of rats following single intratracheal inoculation of the yeast cells. Most of the inoculated cells were cleared from lungs within 48 hr after exposure. Clearance was enhanced in lungs exposed to metal-coated fly ash than in those exposed to native fly ash. The validity of these studies was verified in vitro using peritoneal macrophages of mice exposed in vivo to native and metal-coated fly ash. An increase in phagocytic and intracellular killing of macrophages harvested from animals exposed to native or metal-coated fly ash was observed.

Preliminary studies on the fibrogenic effects of silicotic pulmonary lavage in normal rat lung

Abstract The biological activity of silica free broncho‐pulmonary lavage (BPL) obtained from silicotic rats was determined by injecting intratracheally into fresh group of rats or by exposure to a suspension of sheep erythrocytes. The BPL obtained at 8, 16 and 45 days after silica inoculation, revealed no hemolytic action on sheep red blood corpuscles. However, when injected intratracheally into fresh rats, the BPL caused mild exudative and cellular changes into the alveolar spaces at early periods. At later periods, marked interstitial thickening due to infiltration by mononuclear cells, foamy macrophages and fibroblasts resulted. The 16 day old silicotic BPL involved larger areas of pulmonary parenchyma and caused more fibroblastic proliferation as compared to BPL obtained at other periods.

Pulmonary response to graded doses of coal fly ash in rats

Abstract The effects of an intratracheal inoculation of graded doses of coal fly ash were investigated in the lungs of rats. Animals exposed to increasing concentrations of the dust did not significantly increase the wet and dry weight of lungs. Collagen contents of lungs, estimated as hydroxyproline, increased significantly with lapse in time and was dependent on the dust concentration used. The dust produced a marked macrophage response in the alveoli and a thickening of the interalveolar septa, due to cellular infiltration and proliferation of argyrophilic fibres. Irrespective of the amount of dust injected, foci of dust laden macrophages were present in the mediastinal lymph nodes at all time periods. In the bronchoalveolar lavage the number of cells increased very significantly with an increase in the amount of fly ash injected. Increase in the cellular constituents of the bronchoalveolar lavage was associated with a statistically significant increase in the lactate dehydrogenase enzyme activity and ...