The Specificity of Allergic Reactions

Abstract

Contact hypersensitivity induced by simple chemicals is believed analogous to delayed hypersensitivity because of outstanding similarities between the two. (a) The inflammatory response to surface application of the hapten requires about 24 hours to reach its maximum. Haptens or low molecular substances such as dinitrofluorobenzene or picryl chloride can induce both contact hypersensitivity and circulating antibody in guinea pigs. They are, however, believed to react first with protein in vivo to form a complete antigen (1-3). Intradermal injection of such a hapten in Freund's adjuvant (with or without mycobacteria) induces in guinea pigs a hypersensitivity wherein later surface application of the same chemical produces a local inflammatory response. This contact type responsiveness is believed to be related to, or identical with, delayed hypersensitivity (1).The simple chemicals that induce such hypersensitivity are usually capable of combining in vitro with protein. A proportionality, moreover, exists between the rate of reaction with protein in vitro and the capability of inducing contact skin hypersensitivity (1). Hapten-protein conjugates prepared in vitro, however, do not generally induce contact hypersensitivity to the hapten, but do induce 185

The Specificity of Allergic Reactions

“…Such conjugates, nevertheless, readily induce haptenspecific antibodies (15). Contact hypersensitivity to DNP conjugates has been induced by the inoculation of DNP-gulnea pig red blood cell stromata conjugates in complete adjuvant (19) or by DNP-GPSKIN conjugates in incomplete adjuvant (11). The specificity of a hapten-protein conjugate during the period of delayed hypersensitivity has been demonstrated to be directed primarily toward the protein-carrier (20,21).…”

“…The specificity of a hapten-protein conjugate during the period of delayed hypersensitivity has been demonstrated to be directed primarily toward the protein-carrier (20,21). This type of specificity probably exists in the contact hapten system (11). If, therefore, a conjugate prepared in vitro is to induce contact hypersensitivity, the conjugate must have protein determinants which are similar to those formed in vivo upon application of the hapten to the skin.…”

<i>In vitro </i>DNA Synthesis in Lymphocytes from DNCB Contact-Sensitive Guinea Pigs

“…In contact sensitivity, which is considered to be a form of delayed hyper sensitivity (2,20), the assessment o f in vitro DNA synthesis by lymphocytes from sensitized animals met initially with serious difficulties (7). One of the rea sons was the lack of knowledge about the antigen formed in vivo by conjugation of the hapten with autologous proteins.…”

Hypersensitivity to Chemical Allergens

“…On the other hand, it was reported that the test was significantly less sensitive when animals were challenged after shorter as well as longer latent periods. As a result of these early studies, most investigators have used a latent period of 4-6 hours in critical attempts to detect small quantities of antibody by PCA (11,12). Chase (2) has suggested, however, that latent periods of either 3-6 hours or 17 hours may be equally satisfactory in the elicitation of positive test, and his standard laboratory procedure involves challenge of recipient animals after a latent period of 17 hours.…”

“…Most of the reports describing the use of PCA in the detection of small quantities of antibodies have been based on studies with protein antigens (8,9,12), but the method has been used in the titration of antibodies to chemical allergens (3,11). Results of quantitative studies with antisera to allergenic chemicals, utilizing different latent periods and various allergen-protein conjugates for eliciting PCA have not been reported.…”