Induction of suppressor T cells for lymph node cell proliferation after contact sensitization of mice with a poison oak urushiol component.

Contact sensitivity with properties of delayed-type hypersensitivity (DTH) can be induced in mice by 3-heptadecylcatechol (HDC, a component of poison oak urushiol oil). Sensitization is effected by painting on abdominal skin and is assessed by measuring ear swelling produced after ear challenge. Further studies on the nature of this sensitization were made by monitoring the induction of lymph node cell (LNC) proliferation (as indicated by increased in vitro uptake of [14C]-thymidine into DNA) after cutaneous treatment with HDC. Draining inguinal LNC proliferation peaked 5-6 days after abdominal application of HDC. LNC taken from sensitized mice at times later than this peak suppressed HDC-induced proliferation when transferred into recipient mice. Such suppressor cells were T lymphocytes as implied by their sensitivity to anti-Thy-1.2 antibody and complement. The suppressive effect appeared to have both specific and non-specific components. LNC containing these T suppressor cells could not suppress the optimal proliferation in vitro of previously sensitized cells, nor was suppressive activity observed against the induction of contact sensitization itself. Thus, although the suppressor cells appeared to act on the afferent phase of sensitization, they may not be directed against the effector cells of DTH.