DNA Synthesis <i>in vitro</i> by Cells from Mice Immunized with Picryl Chloride: Effect of Injection of Immune Cells

Abstract

Mice were immunized with picryl chloride and the regional nodes taken at various times afterwards. These cells spontaneously synthesized DNA in vitro as measured by thymidine incorporation over an 18-hour period and the peak incorporation occurred when the cells were taken on day 3. When the mice were injected with cells taken 5 days after immunization with picryl chloride and then immunized, there was a depression of the spontaneous DNA synthesis in vitro. This was absent on day 2, most marked on day 3 and still present on day 4. Cells from donors immunized with 4-ethoxymethylene-2-phenyloxazolone had a smaller but definite effect. Attempts to reproduce the phenomenon by in vitro mixtures of cells taken at various times after immunization in vivo were unsuccessful.

Depression of Lymph Node Cell Proliferation Induced by Oxazolone

“…It has been previously reported that primary epicutaneous exposure to at least some sensitizing chemi cals (picryl chloride and oxazolone) induced a rapid induction of lymphocyte proliferation in draining lymph nodes which was maximal 3 days following ap plication and declined markedly thereafter [1,3,4], Similar results were obtained in the present study in which draining auricular LNC proliferation follow ing topical application of oxazolone to the ear was measured by 3H-TdR incorporation in vitro. Follow ing challenge with several concentrations (5, 1 and 0.5%) of oxazolone, proliferation was maximal in LNC populations isolated 72 h following exposure.…”

“…The proliferative activity of draining auricular lymph nodes was determined 3 days following challenge. A representative experi ment is illustrated in figure 5 and demonstrates that, although maximal contact sensitization required 72 h to develop following primary sensitization, systemic Although a number of previous reports have sug gested that the regulation of lymphocyte proliferative responses induced by topical exposure to chemicals is generally hapten-specific [6], there exist data which argue for at least limited antigenic cross-reactivity [2][3][4], To investigate further the specificity of the in duced depression of lymphocyte proliferation, experi ments were performed with oxazolone and the antigenically non-cross-reactive contact sensitizing chemi cal picryl chloride. Topical application of either chemical resulted in depression of auricular lymph node responses following ear challenge with oxazo lone or picryl chloride.…”

“…Although such studies clearly demonstrate the potential for control of contact allergy, they do not directly address the question of whether the induction of contact sensitiv ity following conventional topical exposure is ac tively regulated. In this context it is of interest that epicutaneous exposure to at least some sensitizing chemi cals including picryl chloride [3][4][5], oxazolone [3] and 3-heptadecylcatechol (HDC) [2] has been reported to result in the appearance of cells which influence the proliferative response. We have re-examined this phenomenon and report that following primary expo sure to oxazolone there is a systemic depression of proliferative responses to topically applied chemical.…”

“…Thus, for in stance, Asherson et al [3] reported a small non-spe cific inhibition of proliferative responses to picryl chloride following the transfer of LNC from oxazolone-treated mice in two of ten experiments. Sim ilarly, Datta et al [4] observed that cells from donors immunized with either picryl chloride or oxazolone had a significant effect on picryl chloride-induced DNA synthetic capacity of draining LNC in recipient mice. A non-specific inhibition has also been reported following exposure of mice to the urushiol oil compo nent HDC.…”

“…There have been a number of demonstrations that the proliferative response to at least some chemicals is ac tively regulated and that lymph node cells (LNC) iso lated from immunized mice will depress proliferation in recipient animals [2][3][4][5]. While depression of lym phocyte proliferative responses in contact sensitivity has, in most circumstances, been regarded as largely antigen-specific in nature [6], there are indications that in some instances non-specific effects may be ob served [2][3][4].…”