Clearance of Plasma Enzymes in Normal and LDH Agent Infected Mice. ∗

Summary

1. Plasma enzyme levels in mice rose rapidly following either intravenous or intraperitoneal injection of enzymes from he-molyzed red blood cells. The increase following i.p. injection represented a rapid and fairly quantitative passage of functionally active proteins across membrane barriers in the host animal into the systemic circulation. It was independent of the RBC donor species. 2. Plasma clearance rates of injected LDH, MDH and GOT were measured in normal mice and in mice infected with an LDH agent from the CD/5 lymphoma. Clearance of exogenously administered enzymes was about double in normal as compared to infected mice. 3. Clearance data used in conjunction with comparative enzyme levels in infected mice eliminate the possibility that a nonspecific virus-induced tissue necrosis is the source of increased plasma enzyme. 4. It is concluded that the increae in certain plasma enzymes following infection with an LDH agent most probably results from an impairment of plasma enzyme clearance mechanisms.