Urushiol (poison ivy)-triggered suppressor T cell clone generated from peripheral blood.

Abstract

Allergic contact dermatitis to Toxicodendron radicans (poison ivy) is mediated by the hapten urushiol. An urushiol-specific, interleukin 2 (IL-2)-dependent T cell clone (RLB9-7) was generated from the peripheral blood of a patient with a history of allergic contact dermatitis to T. radicans. This clone proliferated specifically to both leaf extract and pure urushiol. Although the clone had the phenotype CD3+CD4+CD8', proliferation to antigen was blocked by anti-CD8 and anti-HLA-A, B, C but not by anti-CD4, suggesting that CD4 was not functionally associated with the T cell receptor. Furthermore, studies with antigen-presenting cells from MHC-typed donors indicated that the clone was MHC class 1 restricted. RLB9-7 was WT31 positive, indicating it bears the afi T cell receptor. The clone lacked significant natural killer cell activity and produced only low levels of IL-2 or y-interferon upon antigen stimulation. Addition of RLB9-7 to autologous peripheral blood mononuclear cells in the presence of urushiol inhibited the pokeweed mitogen-driven IgG synthesis. This suppression was resistant to irradiation (2,000 rad) and was not seen when RLB9-7 was added to allogeneic cells, even in the presence of irradiated autologous antigen-presenting cells, suggesting that suppression was MHC restricted and not mediated by nonspecific soluble factors. However, RLB9-7 cells in the presence of urushiol inhibited the synthesis of tetanus toxoid-specific IgG by autologous lymphocytes, indicating that the suppression, although triggered specifically by urushiol, was nonspecific.

Processing of urushiol (poison ivy) hapten by both endogenous and exogenous pathways for presentation to T cells in vitro.

“…Tetanus toxoid-responsive lines were uniformly CD3+ CD4+ CD8-, and urushiol-responsive lines were predominantly CD3+ CD8+ (Table I). This was compatible with our previously published reports on urushiol-specific T cell lines and clones from three individuals (29)(30)(31). Several urushiol-specific lines exhibited a significant proportion of double-positive CD4+ CD8+ cells.…”

“…Several urushiol-specific lines exhibited a significant proportion of double-positive CD4+ CD8+ cells. This has been confirmed with two-color immunofluorescence and reported previously for a urushiolspecific T cell clone (29). Antigen-specific lines from a fourth individual demonstrated similar findings for both urushiol (CD3+ 98%/CD4+ 35%/CD8+ 81%) and tetanus toxoid (CD3+ 93%/CD4+ 93%/CD8+ 3%).…”

“…An additional negative control was provided by the inability of either monensin or brefeldin A to inhibit presentation ofurushiol to the processing-independent CD8+ urushiolspecific lines. The predominance of CD8+ urushiol-specific T cell lines and clones in the urushiol response (29)(30)(31) (45,46). Other allergens such as DNFB evoke a combined CD4+ and CD8+ response (32).…”

“…A high proportion of CD8+ human urushiol-specific T cell clones are CD8+ (29)(30)(31), and class I MHC restriction was demonstrated for one such urushiol-specific clone (29). This suggests that processing of urushiol-conjugated proteins proceeds by the endogenous pathway.…”

Mechanisms and pathology of occupational asthma

“…Recently, it has been reported that soluble exogenous antigens or haptens are able to mount an MHC class I restricted response [36,37].…”