IMMUNOHISTOCHEMICAL DETECTION OF SUBSTANCE-P AND VASOACTIVE-INTESTINAL-PEPTIDE FIBERS IN THE AURICULAR LYMPH-NODES OF SENSITIZED GUINEA-PIGS AND MICE

The presence of substance P (SP) and vasoactive intestinal peptid (VIP ) in auricular lymph nodes of normal and sensitized guinea pigs and mi ce has been investigated using polyclonal antibodies directed against these neurotransmitters and the unlabelled peroxidase-antiperoxidase p rocedure. Positive immunoreactivity could be observed only in draining lymph nodes of sensitized animals. SP-immunoreactivity was found in m ice and guinea pigs but a VIP-positive reaction only in mice. The immu nopositive sites were always associated with blood vessels. The presen t study suggests that the neurotransmitters SP and VIP are involved in mechanisms of sensitization taking place in secondary lymphoid organs .