Dermatologic implications of immunological unresponsiveness

Experimental photoallergy to systemic drugs

We have induced photoallergy in mice to systemically administered drugs, specifically sulfanilamide and chlorpromazine. Mice were photosensitized to systemic sulfanilamide or chlorpromazine by i.p. administration of drug followed by UVB and UVA irradiation of shaved flank skin, on two consecutive days. Control mice received i.p. drug with no irradiation. In some experiments cyclophosphamide pretreatment, or intradermal Corynebacterium parvum (Propionibacterium acnes), was administered as an immunoadjuvant. All animals were photochallenged on day 5 with i.p. drug followed by UVA irradiation of one ear. Mice that had been previously immunized with drug and UV radiation developed ear swelling and erythema, evident 24 h after photochallenge, but not at 4 h. Control animals showed no reactions. In a typical experiment of photosensitization to systemic sulfanilamide, the experimental group had a mean increase in ear thickness of 6.0 X 10(-2) mm 24 h after photochallenge, while unsensitized control animals showed a mean change of -0.8 X 10(-2) mm. The histopathology of the positive challenge reaction was characteristic of a delayed type hypersensitivity. Adoptive transfer of photoallergy to systemic sulfanilamide to naive recipients was accomplished by i.v. injection of lymph node cells (5 X 10(7) harvested from actively photosensitized donors. Clinical reports have suggested that exposure to systemic medications followed by sunlight can induce an eruption having a photoallergic basis. We now report the first experimental proof of that hypothesis. The murine model should facilitate exploration of photoallergic mechanisms and, in addition, it provides the basis for a prospective test of systemic drugs for their photoallergenicity.

Induction of tolerance to DNCB-contact sensitivity in guinea pig fetuses

1. Female guinea pigs made tolerant before pregnancy do not transfer tolerance to their offspring. This result favours the concept of cellular mechanism of tolerance. 2. Guinea pig fetuses become tolerant when exposed to the tolerogen in the last two weeks of pregnancy. This is due to active tolerization by the tolerogen passing the placental barrier. 3. Fetuses exposed to the antigen earlier did not develop tolerance. This is due to immunological immaturity rather than to insufficiently developed vascularization. No functional active depot of tolerogen is formed. 4. Guinea pigs become immunologically mature between the 54th and 61st day of fetal live.

The induction of immune tolerance in delayed contact sensitivity by the use of chemically related substances of low immunogenicity

Immune tolerance in delayed contact sensitivity to pentadecylcatechol can be induced by a series of derivatives substituted in the 6 position of the ring. Some of these derivatives have the property of being very poor sensitizers and having very low dermal toxicity. Thus, sensitization and tolerance have different biologic mechanisms and are associated with different properties of these chemicals.

Contact sensitization of guinea-pigs with unsaturated and halogenated sultones

The sensitizing properties of unsaturated and halogenated sultones were examined in a guinea-pig model for contact hypersensitivity. The sensitization potential of 2-chloro-1,3-dodecanesultone was similar to that of 1-chloro-2,4-dinitrobenzene (DNCB). 2-bromo-1,3-dodecanesultone, 1-decene-1,3-sultone, 1-decene-1,3-sultone, 1-tetradecene-1,3-sultone and 1-hexadecene-1,3-sultone were stronger senistizers than DNCB. Ectensive cross-reactivity was observed among sultones of the same side-chain length, but differing from each other in being either unsaturated or halogenated. Extensive cross-reactivity was also noted among 4 unsaturated sultones of differing side-chain lengths. The inter-relationships among these sultones in regard to their immunogenic and tolerogenic properties are discussed.

Studies on the contact sensitization of man with simple chemicals. III. Quantitative relationships between specific lymphocyte transformation, skin sensitivity, and lymphokine activity in response to dinitrochlorobenzene

Dinitrochlorobenzene (DNCB) coupled to peripheral blood erythrocytes or leukocytes forms a particulate complex, DNCB-antigen. The addition of DNCB-antigen induced blastogenesis and DNA synthesis in leukocyte cultures from DNCB-sensitized human subjects and not in leukocyte cultures from nonsensitized controls. In general, sensitized subjects who displayed a higher degree of cutaneous reactivity to DNCB, as manifested by duration and intensity of dermatitis, also showed a greater blastogenic response to DNCB-antigen in vitro. This quantitative correlation, however, was not invariant. Certain soluble factor(s), or lymphokines are released following the addition of DNCB-antigen to leukocyte cultures prepared from some sensitive subjects who were rechallenged one or more times with DNCB. These lymphokines induce blastogenesis in secondary target leukocyte populations from nonsensitized subjects. Extended studies are presented which slow little or no lymphokine activity in peripheral blood leukocyte cultures during a primary immune response, despite high degrees of blastogenic activity in response to DNCB-antigen. Significant lymphokine activity was observed only following additional rechallenge with DNCB. Blastogenesis and skin reactivity specific for DNCB have been shown to develop at about the same time during a primary immune response. This, along with the quantitative correlation shown in this communication, suggests that both processes probably reflect thymic-dependent cellular immunity. The appearance of lymphokine activity following rechallenge with DNCB suggests that DNCB-induced lymphokines may represent an amplifying mechanism of the cellular immune response that involves recruitment of previously uncommitted lymphocytes.