Arthus and delayed type of hypersensitivity to Pseudomonas aeruginosa antigens in mouse

The time course of footpad swelling in mice of the inbred 129 strain sensitized with the living Pseudomonas aeruginosa or slime extracted from bacteria was studied. Reactions of Arthus type were observed in animals immunized intraperitoneally (i.p.) or intravenously (i.v.) with slime extract and then challenged into the footpad with this preparation. Mice immunized subcutaneously (s.c.) with slime-extract in complete Freund's adjuvant (CAF) and on day 15 challenged into the footpad displayed the swelling characteristic of the delayed-type hypersensitivity (DTH). The delayed onset of reactivity was also seen in mice sensitized with living bacteria into the footpad and then challenged with slime-extract. Maximum DTH reactions were induced in mice challenged on day 14 after priming. The skin infiltration in DTH reacting mice was characteristic of the polysaccharide antigens. At the 24th h following challenge, the predominance of polymorphonuclear (PMN) cells in footpad hypodermis was found as well as heavy infiltration of mononuclear (M) cells.