Leukocyte endogenous mediator is a low molecular-weight
protein synthesized by circulating monocytes and fixed macrophages of the reticuloendothelial system. Exogenous administration of
leukocyte endogenous mediator to a well-nourished animal stimulates both specific and nonspecific immune function and replicates the
protein metabolic response to
infection, characterized by
fever and increased
amino acid oxidation, skeletal protein degradation and synthesis of "
acute-phase" proteins.
Leukocyte endogenous mediator administration also affords protection against semi-lethal doses of
bacteremia in the well-nourished animal. In the
protein-depleted host, synthesis or release of
leukocyte endogenous mediator in response to
infection appears to be reduced and the attenuated metabolic response may be attributed, in part, to a deficit in its production. However, nutritional repletion of the malnourished patient results in restoration of the capacity to produce
leukocyte endogenous mediator usually within three to seven days, if adequate
dietary protein is provided. Since
protein malnutrition is associated with increased incidence and severity of
bacterial infections, we postulate that the reduced synthesis and/or release of
leukocyte endogenous mediator in
protein malnutrition is detrimental. In those
critically-ill, malnourished patients who cannot endogenously synthesize
leukocyte endogenous mediator, and for clinical reasons cannot be repleted rapidly or are already infected and/or undergoing operative stress, exogenous administration of
leukocyte endogenous mediator should be considered along with
nutritional support. Administration of this
protein to a seriously-ill malnourished individual should produce a metabolic profile of
fever, increased urinary
nitrogen excretion and falls in
serum albumin concentrations that are generally considered pathologic. However, administration of
leukocyte endogenous mediator over short periods of time should also provide the anabolic impetus for the augmented synthesis of
proteins beneficial to recovery.(ABSTRACT TRUNCATED AT 400 WORDS)