Comparison of Leukocytic Pyrogen and Leukocytic Endogenous Mediator

Abstract

Leukocytic pyrogen was subjected to a five-step purification scheme, and quantitative assays for both leukocytic pyrogen and leukocytic endogenous mediator (LEM) were made. At each step of the purification scheme, the active fractions, in addition to producing fever, lowered plasma iron and zinc concentrations, elevated fi-brinogen concentrations, and caused a release of neutrophils from bone marrow. It appears, therefore, that LEM and leukocytic pyrogen are the same molecule.