An antigen-specific hypersensitivity which does not fit into traditional classification of hypersensitivity

A unique type of Ag-specific hypersensitivity was induced by challenging the Ag-sensitized mice at the ear. It was elicited within 1 h after the Ag challenge, and thus was distinct from either the delayed-type hypersensitivity (DTH) which developed in 24 h or the immune complex-mediated hypersensitivity which evolved in 4 to 6 h. This hypersensitivity was referred to as early-type hypersensitivity (ETH). The time required for these types of hypersensitivity to develop after immunization was also different; DTH required 4 to 6 days, ETH 9 to 11 days, whereas plasma protein-induced immune complex-mediated hypersensitivity needed 18 to 21 days. The ETH could be induced by a smaller amount of Ag than DTH, and unlike DTH could be transferred by either immune sera or T cell-derived culture factor which was small m.w. Although the ETH developed later than DTH after sensitization, it lasted longer once developed and the pattern of response was inversely related to DTH. Furthermore, the denatured hepatitis B surface Ag induced DTH but not ETH, in contrast to native hepatitis B surface Ag that induced both, suggesting that the epitopes recognized by TETH cells were distinct from those recognized by TDTH cells. The ETH could be induced by most Ag tested including poly(Glu60Ala10Tyr10, L-lactic dehydrogenase, insulin, chicken egg white lysozyme, polymerized human serum albumin, horse gamma-globulin, transferrin, fibrinogen, and plasminogen, but not by purified protein derivative. Because poly(Glu60Ala10Tyr10, L-lactic dehydrogenase, egg white lysozyme and insulin were under the Ir gene control and the inducibility of ETH was Ag dependent and was closely correlated with that of DTH, the expression of ETH also must be regulated by Ir gene. The histopathologic changes in ETH consisted of capillary congestion and edema. The vasopermeability was increased and there was the leakage of plasma proteins into the tissue. Based on these data, we concluded that the ETH reported in this study was a novel type of Ag-specific hypersensitivity.