Squaric acid dibutyl ester (SADBE) is a known contact sensitizer, but dose-response data are not defined.
Objective:
To determine the relationship between sensitization dose and contact hypersensitivity (CHS) response to SADBE in human volunteers. The study also aimed to investigate whether SADBE-reactive blood T cells could be detected using ex vivo mature dendritic cells (DCs) as antigen-presenting cells.
Method:
Forty healthy volunteers were sensitized to either 12.5, 25, 50, or 250 μg of SADBE in a 48 μL volume. This was followed by elicitation 2 weeks later with five doses (0, 0.2, 2, 20, and 200 μg in 20 μL). An additional 10 subjects received the elicitation doses without prior sensitization. Blood samples obtained after sensitization were purified into T cells and mature DCs.
Results:
A direct relationship between sensitization dose and in vivo CHS response was observed. The SADBE dose that effectively sensitized 50% of the population (ED50) was 22 μg/cm2. Significant SADBE-specific T-cell proliferation in vitro was not observed 2 weeks after sensitization but became evident after elicitation.
Conclusion:
This study establishes the in vivo dose-response characteristics of immune reactivity to SADBE and antigen-specific T-cell reactivity.
GardnerS, Freyschmidt-PaulP, HoffmannR, et al.Normalisation of hair follicle morphology in C3H/HeJ alopecia areata mice after treatment with squaric acid dibutylester. Eur J Dermatol, 2000; 10: 443-50.
3.
IijimaS, OtsukaF. Prognostic factors for clinical response of alopecia areata to topical immunotherapy with squaric acid dibutylester. Arch Dermatol, 1997; 133:539-40.
4.
MicaliG, CiceroRL, NascaMR, SapuppoA. Treatment of alopecia areata with squaric acid dibutylester. Int J Dermatol, 1996; 35:52-6.
5.
RokhsarCK, ShupackJL, VafaiJJ, WashenikK. Efficacy of topical sensitizers in the treatment of alopecia areata. J Am Acad Dermatol, 1998; 39(5 Pt 1):751-61.
6.
SilverbergNB, LimJK, PallerAS, ManciniAJ. Squaric acid immunotherapy for warts in children. J Am Acad Dermatol, 2000; 42(5 Pt 1):803-8.
7.
MastrolonardoM, LopalcoPL, DiaferioA. Topical immunotherapy with contact sensitizers: a model to study the natural history of delayed hypersensitivity. Contact Dermatitis, 2002; 47:210-4.
8.
FriedmannPS, MossC, ShusterS, SimpsonJM. Quantitative relationships between sensitizing dose of DNCB and reactivity in normal subjects. Clin Exp Immunol, 1983; 53:709-15.
9.
WhiteSI, FriedmannPS, MossC, SimpsonJM. The effect of altering area of application and dose per unit area on sensitization by DNCB. Br J Dermatol, 1986; 115:663-8.
10.
ReesJL, FriedmannPS, MatthewsJN. Sex differences in susceptibility to development of contact hypersensitivity to dinitrochlorobenzene (DNCB). Br J Dermatol, 1989; 120:371-4.
11.
MicaliG, Dall'OglioF, TedeschiA, et al.Treatment of cutaneous warts with squaric acid dibutylester: a decade of experience. Arch Dermatol, 2000; 136:557-8.
12.
BenderA, SappM, SchulerG, et al.Improved methods for the generation of dendritic cells from nonproliferating progenitors in human blood. J Immunol Methods, 1996; 196:121-35.
13.
LenzA, HeineM, SchulerG, RomaniN. Human and murine dermis contain dendritic cells. Isolation by means of a novel method and phenotypical and functional characterization. J Clin Invest, 1993; 92:2587-96.
14.
RomaniN, GrunerS, BrangD, et al.Proliferating dendritic cell progenitors in human blood. J Exp Med, 1994; 180:83-93.
15.
RomaniN, ReiderD, HeuerM, et al.Generation of mature dendritic cells from human blood. An improved method with special regard to clinical applicability. J Immunol Methods, 1996; 196:137-51.
16.
SallustoF, LanzavecchiaA. Efficient presentation of soluble antigen by cultured human dendritic cells is maintained by granulocyte/ macrophage colony-stimulating factor plus interleukin 4 and downregulated by tumor necrosis factor alpha. J Exp Med, 1994; 179:1109-18.
17.
RyanCA, HuletteBC, GerberickGF. Approaches for the development of cell-based in vitro methods for contact sensitization. Toxicol In Vitro, 2001; 15:43-55.
