Lactate dehydrogenase isoenzymes in macrophages and serum during the development of pulmonary silicosis in the rat.

The lactate dehydrogenase (LDH) isoenzyme pattern in macrophages (peritoneal and alveolar) in the rat was studied on polyacrylamide gel electrophoresis. Further, the release of LDH isoenzymes from cultured macrophages exposed to silica dust and also the pattern of serum LDH isoenzymes in silica exposed animals were investigated. The isoenzyme pattern of the alveolar macrophages showed all the five bands, contrary to peritoneal macrophages in which two bands, viz. LDH1 and LDH2, were missing. Silica-exposed macrophages liberated LDH5 in the supernatant culture medium. This LDH isoenzyme also increased in the serum of silicotic rats during the early stages of the development of the disease.