Studies in staphylococcal fever. VI. Responses induced by cell walls and various fractions of staphylococci and their products.

In earlier papers of this series`~5 we have shown that cultures of Staphylococcus aureus when injected intravenously into rabbits produce fever by two different mechanisms. The cell bodies of this organism, in common with those of other Gram-positive bacteria, caused fevers that appeared after a characteristic latency of 45 to 60 minutes. The febrile responses were roughly proportional to the number of organisms injected, above a minimal pyrogenic dose of 1 x 107. Since autoclaved bacteria were equally pyrogenic, fever was clearly independent of infection and appeared to be caused by phagocytosis of the injected bacteria by circulating leukocytes. A second pyrogenic factor was found to be present in culture filtrates of staphylococci belonging to certain phage types. Although the responses to this agent were indistinguishable from those induced by the cell bodies, several lines of evidence indicated that the soluble agent was an antigenic protein that produced fever by means of a naturally acquired or experimentally induced hypersensitivity of the delayed type.2` The present studies were carried out with several partially purified fractions of staphylococci of two strains (Giorgio and 80-81) in an attempt to determine further the relation between these pyrogenic factors and the mechanisms by which they produce fever.