Observations on the Production of Pyrogenic Substances by Rabbit and Human Leucocytes

Abstract

1. The mechanism of release of a pyrogen from leucocytes has been studied in cells obtained from sterile rabbit peritoneal exudates and from rabbit blood. Attempts were made to induce human leucocytes—from blood—to release a pyrogen. 2. Rabbit leucocytes, kept below 4°C., were not pyrogenic and did not release any pyrogen when disintegrated. Incubating such cells, in various media, at 37°C. led to the formation of a pyrogen which was heat-labile. The maximum yield was attained after 1½ hours' incubation. 3. The formation of rabbit leucocytic pyrogen was prevented by freezing and thawing the leucocytes, by heating them to 56°C. for half an hour before incubation, and by ageing them in the cold. 4. Nitrofurazone (5-nitro-2-furaldehyde semicarbazone) prevents the formation of leucocytic pyrogen when given by mouth to the cell-donor animals, or when added to leucocytes in intro. 5. Leucocytes from rabbit blood formed leucocytic pyrogen, on incubation in saline, and this formation was also inhibited by nitrofurazone. 6. No leucocytic pyrogen was released from human leucocytes subjected to mechanical, osmotic, or thermal damage, and it was not formed when the cells were incubated in saline. 7. The source of rabbit leucocytic pyrogen, the action of nitrofurazone on leucocytes, and the supposed role of leucocytic pyrogen in fever are discussed.

Studies on the Pathogenesis of Fever

“…The difference recorded, however, was smaller than in the present study and the authors did not consider it to be significant (16).…”

“…The activation phenomenon will be described in a later publication (18). Its existence suggests a possible explanation for the failure of human leucocytes to generate detectable amounts of pyrogen when incubated in saline (16), since the only cells thus far tested have been obtained from the blood.…”

Studies on the Origin of Human Leukocytic Pyrogen

“…In contrast to cells derived from inflammatory exudates, rabbit and human blood leukocytes ~ not release pyrogen spontaneously unless activated by a specific stimulus such as phagocytosis (2,12,14,25) or exposure to various agents, including endotoxin (2,14,26,27) and etiocholanolone (28,29). Two phases appear to be involved in the elaboration of pyrogen by stimulated cells.…”

“…Chemical characterization of LP has shown it to be a protein molecule (6)(7)(8) and since the original discovery of its production by rabbit peritoneal exudate cells (9), many attempts have been made to determine the mechanism of its synthesis by leukocytes. With one exception (10), preformed pyrogen has not been obtained from disrupted rabbit cells (11,12). Its release in vitro has been shown to take place over a several hour period (4,11,12), to be dependent upon the temperature of incubation (11), and inhibited by agents which bind sulfhydryl groups in enzymes (13).…”

“…With one exception (10), preformed pyrogen has not been obtained from disrupted rabbit cells (11,12). Its release in vitro has been shown to take place over a several hour period (4,11,12), to be dependent upon the temperature of incubation (11), and inhibited by agents which bind sulfhydryl groups in enzymes (13). These findings suggest that LP is either synthesized de novo or activated from a precursor substance after contact with an appropriate stimulating agent.…”