Contact sensitivity in the pig. III. Induction by intralymphatic infusion of DNP-conjugated cell membranes and soluble proteins, free DNFB and some small molecular weight derivatives.

DNP-conjugated lymph node cell plasma membranes, thymocyte plasma membranes and red cell ghosts were prepared and tested for their ability to induce contact sensitivity, using pigs as experimental animals. Lymph node cell membranes and red cell ghosts were able to sensitize, provided the dose of DNP was very large, but thymocyte membrane failed to sensitize most pigs. DNP-conjugated lymph proteins coming from the site of application of DNFB were also able to sensitize if large amounts were administered, but free DNFB itself, infused directly into an afferent lymphatic, was much more efficient. Since DNFB can often be detected in lymph folowing skin painting, it may conjugate cells within the node which later contact the recirculating population of lymphocytes and so sensitize the animal by a central mechanism. The best-equipped cells would be the macrophage-like lymph cells which are closely related to the epidermal Langerhans cells and are known to migrate to the paracortex of the node.