title: Pathogenesis of pleural plaques. Relationship of early cellular response and pathology.
abstract: To study the initial pleural cellular response to asbestos and to determine the relationship between this response and the development of pleural plaques, a model of asbestos pleurisy was developed in both normal and nitrogen-mustard-treated (neutropenic) New Zealand white rabbits. Animals were rendered neutropenic, as it has been shown that neutropenic rabbits do not develop a macrophage influx in the pleural space after the administration of either BCG or bacteria and that the pathology is different from that in normal rabbits treated in a similar fashion. Intrapleural asbestos induced an exudative effusion in normal animals within 4 h, and there was increased metabolic activity through 120 h, with a fall in pleural fluid pH and PO2 and a rise in pleural fluid PCO2. Neutropenic animals similarly developed an exudative pleural effusion but showed no change in metabolic activity of pleural fluid. Normal rabbits showed a marked cellular influx into the pleural space after asbestos treatment, with a peak total cell count of 27,208/microliters at 24 h; the majority of these cells were polymorphonuclear leukocytes. A macrophage influx occurred at 48 h and peaked at 72 h. By 120 h, lymphocytes were the predominant cell. Nitrogen-mustard-treated animals reached a peak of only 5,442 cells/microliters in the pleural space at 24 h, with a small percentage of polymorphonuclear leukocytes. A macrophage peak did not occur in these animals. There was a marked contrast between groups noted at autopsy. Normal animals developed pleural plaque formation, which was evident by 7 days and completely developed by 1 month.(ABSTRACT TRUNCATED AT 250 WORDS)
mesh_terms: D000818:Animals; D001195:Asbestosis / Q000276:immunology / Q000473:pathology*; D002452:Cell Count; D007958:Leukocyte Count; D008264:Macrophages / Q000473:pathology; D008466:Mechlorethamine; D009503:Neutropenia / Q000139:chemically induced; D009504:Neutrophils / Q000473:pathology; D010994:Pleura / Q000473:pathology*; D010996:Pleural Effusion / Q000378:metabolism / Q000473:pathology; D010998:Pleurisy / Q000276:immunology / Q000473:pathology*; D011817:Rabbits; D013997:Time Factors
chemical_list: D008466:Mechlorethamine