Determination of in vivo dose response and allergen-specific T cells in subjects contact-sensitized to squaric acid dibutyl ester.
BACKGROUND
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.


METHODS
Forty healthy volunteers were sensitized to either 12.5, 25, 50, or 250 microg of SADBE in a 48 microL volume. This was followed by elicitation 2 weeks later with five doses (0, 0.2, 2, 20, and 200 microg in 20 microL). 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 microg/cm2. Significant SADBE-specific T-cell proliferation in vitro was not observed 2 weeks after sensitization but became evident after elicitation.


CONCLUSIONS
This study establishes the in vivo dose-response characteristics of immune reactivity to SADBE and antigen-specific T-cell reactivity.
Camouse
Melissa M
MM
University Hospitals of Cleveland/Case Medical Center, Cleveland, OH, USA.
Swick
Alan R
AR
Ryan
Cindy A
CA
Hulette
Ben
B
Gerberick
Frank
F
Tinkle
Sally S
SS
Nedorost
Susan T
ST
Cooper
Kein D
KD
Stevens
Seth R
SR
Baron
Elma D
ED
D000276:Adjuvants, Immunologic / Q000008:administration & dosage* / Q000009:adverse effects; D000293:Adolescent; D000328:Adult; D049109:Cell Proliferation; D018920:Coculture Techniques; D003503:Cyclobutanes / Q000008:administration & dosage / Q000009:adverse effects / Q000276:immunology*; D003713:Dendritic Cells / Q000276:immunology; D017449:Dermatitis, Allergic Contact / Q000209:etiology / Q000276:immunology*; D004306:Dose-Response Relationship, Immunologic; D005260:Female; D006801:Humans; D007114:Immunization; D008297:Male; D008875:Middle Aged; D012867:Skin / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology
D000276:Adjuvants, Immunologic; D003503:Cyclobutanes; C020637:squaric acid dibutyl ester