Algerian ivy dermatitis; a California disease

A hitherto unrecognized cause of contact dermatitis in California is the widely cultivated plant known as Algerian ivy. This plant, which grows in California (and its close relative, English ivy) causes a dermatitis which is similar to although milder than that caused by poison oak. Dermatitis from this cause occurs most frequently when persons who have become sensitive to it by previous contact trim the plant back in the spring after its seasonal spurt of growth. For persons whose occupations require repeated contact with the plant, dermatitis from this cause is an occupational hazard. Dermatitis from this plant is easily diagnosed by means of a simple patch test. In a series of 12 cases the only effective treatment was with corticosteroid agents.     

Enrichment and function of urushiol (poison ivy)-specific T lymphocytes in lesions of allergic contact dermatitis to urushiol

The frequencies of urushiol (poison ivy)-specific T cells were determined in the lesional skin and peripheral blood of patients with allergic contact dermatitis to urushiol. Lesions of urushiol dermatitis were biopsied and the T cells retrieved. Frequencies of Ag-specific cells were determined by limiting dilution assay. Enrichment of urushiol specific T cells was detected in lesional skin or blister fluid of five of five of these donors as well as seven of seven donors with urushiol patch tests. There was also enrichment relative to tetanus toxoid specific T cells in blood and skin of six of seven donors. The frequency of lesional T cells specific for urushiol was less than 1/100 and generally less than 1/1000. Furthermore, the frequency of urushiol specific T cells was often less than 1/10,000 in the peripheral blood during an acute eruption. Autoreactive T cells that proliferated to autologous irradiated PBMC were also enriched in skin lesions relative to blood in 5/5 urushiol patch tests. These autoreactive T cells were expanded and found to be CD4+. It has been proposed that such autoreactive T cells recognize autologous DR and may have a role in immunoregulation. Urushiol-specific T cells were expanded from limiting dilution wells of two donors and characterized. The majority of the urushiol-specific cells were CD8+, and 13/43 lines were suppressive for PWM-induced IgG synthesis.     

Patterns of adventitious root formation in English ivy

Adventitious root formation by debladed petiole cuttings of English ivy (Hedera helix L.) proceeds via a direct rooting pattern for the easy-to-root juvenile phase, while the difficult-to-root mature phase roots through an indirect rooting pattern. Juvenile petiole cuttings treated with α-naphthaleneacetic acid (NAA, 100 μM) plus the polyamine biosynthesis inhibitor, difluoromethylarginine (DFMA, 1 mM), formed an increased number of roots per cutting initiated by the indirect rooting pattern. The increased root formation and change in rooting pattern were reversed by the addition of putrescine (1 mM). Delaying auxin application to petiole cuttings for 15 days also induced juvenile petioles to root by the indirect pattern. This could be reversed by rewounding the base of the cutting prior to auxin application after day 15. The data support the use of the terms “competent root-forming cells” and “induced competent root-forming cells” to describe the target cells for the initial events of root formation for the direct and indirect rooting patterns, respectively.