Guinea pigs sensitized with washed, Formalin-killed cells of Staphylococcus aureus, strains 263 or Copenhagen, were skin-tested with various antigens from these strains including washed viable and heat-killed whole cells, cell walls, the peptidoglycan complexes of the walls, teichoic acid, teichoic acid-peptidoglycan fragments, and peptidoglycan fragments. In nonsensitized control animals, all antigens but teichoic acid elicited acute inflammatory reactions which decreased in size after 10 hr. In animals sensitized with the Copenhagen strain, the reactions to all antigens but teichoic acid and peptidoglycan fragments from either strain remained erythematous and indurated for at least 30 hr and were interpreted as hypersensitivity of the delayed type. Responses in animals sensitized with strain 263 generally resembled those in controls, although in some experiments there was evidence of hypersensitivity.The lesions produced by infection with Staphylococcus aureus have been associated with a large number of factors, including the ability of the parasite to elaborate toxins, the presence of antiphagocyte surface structures (7), and an "aggressin" from the cell wall (10). Host response, involving early inflammation (2), immediate hypersensitivity to mural teichoic acid (17), and hypersensitivity of the delayed type (3,12,13,18,23) have all been implicated in pathogenesis in several model systems. Investigations of delayed hypersensitivity have, to this time, all been made with whole cells (3), unfractionated preparations of disintegrated cells (23), or lysates (18). We report here the responses of normal and previously sensitized guinea pigs to intradermal injection with whole cells, cell walls, the mural peptidoglycan complex as well as enzymatically solubilized, chromatographically purified subunits of the cell walls.
NIATERIALS AND METHODSAntigens. Saline suspensions of washed whole cells were prepared from S. aureus strains 263 and Copenhagen grown in Brain Heart Infusion broth (Difco). Half of each suspension was heated in a water bath at 60 C for 30 or 45 min. The suspensions contained 109 colony-forming units (CFU)/ml or their equivalent in heated cells.Particulate antigens included crude and trypsinribonuclease-digested cell walls and their insoluble 'Present address: