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 sensitivity (CS) response to poison ivy/oak could be downregulated following treatment with a monoclonal antibody (mAb) reacting with the allergen urushiol. Conjugation of urushiol and its synthetic analogue 3-n-pentadecylcatechol (PDC) to N-acetylcysteine yielded hydrosoluble derivatives which induced humoral immune responses in BALB/c mice. Hybridomas secreting monoclonal antibodies (mAbs) reacting with urushiol and PDC were generated by fusion of B lymphocytes 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 catechol moiety of urushiol, the region of the allergen being critically important 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. Suppression of CS was most effective with low doses (1 microg) of mAb incorporated into a vaccine with Freund's adjuvant. This treatment suppressed CS responses in BALB/c mice already sensitized to urushiol.