Effects of inhaled hexachlorobenzene aerosols on rat pulmonary host defenses

Pulmonary bactericidal activity, macrophage phagocytic activity, alveolar macrophage (AM) enzyme activity, and T- and B-cell mitogenesis of lymphocytes from lung associated lymph nodes (LALN) or mesenteric lymph nodes (MESLN) were assessed in Sprague-Dawley rats exposed 4 hr/d, 4 days/wk for 1, 4, or 16 days to hexachlorobenzene (HCB) aerosols. Pulmonary bactericidal activity was depressed after 1 or 4 but not 16 exposures to 35 mg/m3 of HCB. AM phagocytosis of 51Cr-RBC in vitro was increased after 4 but not 1 or 16 exposures to HCB, and no effect was observed in peritoneal macrophages. HCB significantly enhanced mitogenesis in MESLN to the B-cell mitogen Salmonella typhimurium lipopolysaccharide (STM) after 4 exposures; LALN STM mitogenesis and LALN and MESLN mitogenesis to phytohemagglutinin (PHA) were not affected. After 16 exposures, however, the PHA responses in LALN and MESLN were significantly increased and decreased, respectively.