2088 Induction of Delayed - Type Hypersensitivity

Delayed-type hypersensitivity (DTH) 1 is a T cell-mediated reaction resulting in a mononuclear cell-rich inf lammat ion and swelling that peak 24-48 h after local antigenic challenge. In spite of the extensive use of D T H to dissect regulatory (1), genetic (2), and molecular (3) aspects of in vivo T cell responses, little is known of factors that regulate the persistence o f these reactions. It is thought that granulomata , such as those seen in tuberculosis and schistosomiasis, provide an example of prolonged D T H (4, 5) resulting from either the persistence of antigen (6) or from the absence of regulatory factors that promote the decay of D T H (7). An experimental model of prolonged T cell-dependent inf lammation, in which a nonpersistent form of antigen is used, would allow an easier dissection of these regulatory factors and perhaps lead to maneuvers that abort some inf lammatory responses. In this paper we show that adminis t rat ion of pertussigen, a purified protein from Bordetella pertussis (8), leads to intense and persistent D T H lesions in mice that are sensitized either actively or passively to protein antigens.