Lysozyme levels in rabbit lung after inhalation of nickel, cadmium, cobalt, and copper chlorides.

Groups of rabbits were exposed to chlorides of nickel, cadmium, copper, and cobalt at concentrations ranging from 0.2 to 0.6 mg/m3 (as metal) for 4-6 weeks (5 days/week, 6 hr/day). Activity of lysozyme (muramidase) in lavage fluid, in alveolar macrophages, and in culture medium from macrophages incubated at 37 degrees C for 1 and 20 hr was estimated using the lyso-plate technique, agar plates with heat-killed Micrococcus lysodeikticus. In the nickel-exposed rabbits lysozyme activity in the mucous membrane from the left main bronchus was also estimated. Following nickel exposure the lysozyme level was significantly decreased in lavage fluid, macrophages, and in culture medium from incubated macrophages but remained unchanged in the mucous membrane. After exposure to cadmium, copper, and cobalt, lysozyme levels increased or were unchanged.