Regulation of the contact sensitivity response to urushiol with anti-urushiol monoclonal antibody ALG 991

The objective of the studies was to demonstrate that the contact sensitivit y (CS) response to poison ivy/oak could be downregulated following treatmen t with a monoclonal antibody (mAb) reacting with the allergen urushiol, Con jugation of urushiol and its synthetic analogue 3-n-pentadecylcatechol (PDC ) to N-acetylcysteine yielded hydrosoluble derivatives which induced humora l immune responses in BALB/c mice. Hybridomas secreting monoclonal antibodi es (mAbs) reacting with urushiol and PDC were generated by fusion of B lymp hocytes from immunized mice with mouse myeloma P3NS0 cells. The specificity of mAb ALG 991 (IgM isotype) was defined by inhibition of antibody binding by PDC analogues. This demonstrated that mAb ALG 991 reacted with the cate chol moiety of urushiol, the region of the allergen being critically import ant in the induction of contact dermatitis. The CS response to urushiol in BALB/c mice was suppressed by stimulation with mAb ALG 991 and the role of sensitized T cells, including suppressor T cells, has been considered, Supp ression of CS was most effective with low doses (1 mu g) of mAb incorporate d into a vaccine with Freund's adjuvant, This treatment suppressed CS respo nses in BALB/c mice already sensitized to urushiol.