Effects of pertussis toxin (PT) on T-cell populations sensitized for delayed-type hypersensitivity in mice

Effects of pertussis toxin (PT) on sensitized T-cell populations for delayed-type hypersensitivity (DTH) were examined in mice. DTH was induced by sensitizing mice with ovalbumin (OA) and elicited by injecting OA into the footpad. DTH could be conferred on naive recipient mice by injecting sensitized spleen cells either intravenously into mice or locally into the footpad. When the sensitized mice were given PT at the time of DTH-elicitation, they did not express a high DTH reaction, with the maximum reaction 24 hr after elicitation. When the recipient mice were given PT just before intravenous injection of sensitized spleen cells, DTH was not conferred. In addition, when the sensitized spleen cells were treated with PT in vitro and then transferred intravenously, DTH was not conferred in recipient mice. However, DTH was conferred by local transfer of the sensitized spleen cells even after treatment with PT in vitro. Migration experiments using 51Cr-labeled, sensitized splenic T cells demonstrated that PT treatment of the T-cell population inhibited its accumulation in the DTH reaction site 24 hr after intravenous transfer. On the other hand, experiments on in vitro lymphokine production by the sensitized splenic T cells demonstrated that the PT treatment did not inhibit antigen-dependent production of a macrophage activating factor (MAF). These results suggest that PT suppresses the migration of the sensitized T-cell population from the circulation of the DTH reaction site but not their MAF production. Based on these findings, possible mechanisms by which PT affects DTH are discussed.