Elevated plasma activity of lactate dehydrogenase isoenzyme-3 (LDH 3 ) in experimentally induced immunologic lung injury.

Normal rats injected intravenously with rabbit antiserum to rat lung develop acute pulmonary lesions characterized by an altered vascular permeability. In the present study, an increase in plasma LDH(3) activity is shown to be positively correlated with the different levels of circulating antilung antibodies and with the morphologic severity of lung injury elicited by these pathogenic immunoglobulins. Within 24 hours, the acute lung changes are resolved, accompanied by a return of the activities of plasma LDH isoenzymes to normal. It is proposed that the plasma LDH(3) isoenzymes are released into the circulation from injured alveolar capillary endothelial cells.