Immunologic tolerance: role of the regional lymph node.

Dansyl chloride, a skin setnsitizer when injected in complete Freund's adjuvant, induced marked tolerance and no sensitization when applied to the intact skin of guinea pigs. Application of this chemical to alymphatic skin islands failed to induce tolerance or sensitization. Lymnphatic connections between skin and regional lymph nodes were essential for the developmnent of ismmunologic toleance.