The Journal of Experimental Medicine, Vol 135, 357-375,
Copyright © 1972 by The Rockefeller University Press
STUDIES ON THE SENSITIZATION OF ANIMALS WITH SIMPLE CHEMICAL COMPOUNDS
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XIII. SENSITIZATION OF GUINEA PIGS WITH PICRIC ACID
Henry C. Maguire Jr. 1 and
Merrill W. Chase 1
1 From The Rockefeller University, New York 10021, and The Hahnemann Medical College and Hospital, Philadelphia, Pennsylvania 19102
A method of establishing regular and intense sensitivity to picric acid is described, based upon an initial sensitization by a "split-adjuvant" technique in which the intradermal injection of mycobacteria in paraffin oil precedes or follows the administration of allergen to the same sites. When subsequent contact applications of picric acid are later made, the degree of sensitivity rises in steps such that reactivity occurs in tests made with low concentrations of picric acid, in the range of 0.060.006% but varying somewhat from one experiment to another. This heightening of picric acid reactivity represents an anamnestic response in the area of delayed hypersensitivity.
The characteristics of contact reactions to the weak allergen, picric acid, differ from those encountered with covalently binding haptens, PCI and DNCB. A slow evolution from an initial micropapular reaction to full reaction requires about 3 days, leading often to a micaceous scale, with histological evidence of vesiculation even while the reaction is still feeble, and to an infiltrate containing a significant number of polymorphonuclear leukocytes.
Substitution of an emulsion of picric acid in complete Freund's adjuvant as a priming experience proved to be much less efficient.
The split-adjuvant technique offers a general plan for sensitizing with weak allergens. Indeed, technically, sensitization can be acquired even when, for priming, the allergen is applied topically over intradermal depots of mycobacteria in paraffin oil. Compatibility between sensitizer and adjuvant is not required.
Submitted on September 13, 1971