Induction in the guinea pig of delayed hypersensitivity to compound 48/80

Intradermal injection of compound 48/80 into the nuchal area of the guinea pig in an adjuvant/water emulsion induced strong delayed hypersensitivity. Groups of 8 animals were injected weekly for 3 weeks with 100 microliter of 10%, 1%, 0.1% or 0% of compound 48/80 in the adjuvant/water emulsion. 6 of 8 animals in the highest concentration group died between 1 and 24 h after the first injection. The other concentrations produced no visible evidence of acute toxicity. 2 weeks after the last injection, the animals were challenged with an open topical application of 1%, 0.1%, 0.01%, and 0% of compound 48/80 in 3:7 propylene glycol/ethanol. The strongest reactions were found in the 0.1% induction group. Some degree of immunologic tolerance may have occurred in the 1% induction group resulting in somewhat weaker challenge responses.     

Ultraviolet-B radiation suppresses mast cell degranulation induced by compound 48/80

This study was designed to investigate the effect of middle-wave ultraviolet (UVB) radiation on mast cell functions using mouse ear skin as an in vivo model. Groups of UVB-irradiated BALB/c mice were given an intradermal injection of the mast cell degranulator compound 48/80 into ears at various time intervals (30 min-7 days) after a single exposure to a bank of fluorescent sunlamp tubes (10-100 mJ/cm2). Both the compound-evoked ear swelling response (ESR) and mast cell degranulation were significantly suppressed by preexposure to UVB (25-100 mJ/cm2) after 0 (30 min) to 3 days postirradiation, with a subsequent recovery by day 7. No such effects were observed in mice irradiated with 10 mJ/cm2. The ESR induced by 5-hydroxytryptamine was not significantly affected by UVB radiation during the experimental period. While within this dose range UV radiation itself caused neither loss of mast cell counts nor a measurable degree of degranulation in ear skin, exposure to larger amounts of UV energy (200-500 mJ/cm2) produced tremendous ear swelling with histologic features of mast cell degranulation in an early phase of inflammation. The results suggest that UVB radiation exerts a dual effect on mast cells and that administration of smaller amounts of UVB may alter the mast cell/vasoactive amine system, suppressing ear swelling in response to the degranulator. Vascular reactivities to vasoactive amines were not affected by UVB irradiation.     

Attenuation of axon reflexes to compound 48/80 after repeated iontophoresis of compound 48/80 in skin of the human forearm

The aim of this study was to determine whether the iontophoretic administration of the mast cell degranulator compound 48/80 influences axon reflex vasodilatation in the skin of the human forearm. In stage 1, compound 48/80 was administered by iontophoresis to a circular site in the forearm of 9 healthy men and 8 healthy women on four occasions spread over 24 h. Two control sites were also prepared by passing the iontophoretic current through 0.9% saline. Large wheals initially developed at the compound 48/80 site in 8 of the males and in 2 of the females, but wheals were minimal in all subjects by the fourth administration. In stage 2, compound 48/80 iontophoresis provoked substantial flaring at the first control site, whereas saline iontophoresis induced only minor flaring at the second control site, indicating that compound 48/80 induced axon reflex vasodilatation. However, prior treatment with compound 48/80 inhibited flaring to compound 48/80 in subjects who initially developed wheals, consistent with mast cell degranulation. In stage 3, flaring after iontophoresis of histamine was investigated at the site of compound 48/80 pretreatment and at the second control site in 12 subjects. Flaring was impaired only slightly in 6 subjects who initially developed wheals to compound 48/80. The persistence of flaring indicates that repeated administrations of compound 48/80 did not abolish neurogenic inflammation. Transcutaneous iontophoresis of compound 48/80 may be an attractive alternative to intradermal injection in studies that aim at clarifying the function of mast cells in healthy and diseased skin.     

Substance P- and antigen-induced release of leukotriene B4, prostaglandin D2 and histamine from guinea pig skin by different mechanisms in vitro

Abstract Substance P (SP) induces increased vascular permeability, vasodilatation and granulocyte infiltration upon intradermal injection. Studies with antagonists and mast cell-deficient mice have suggested that granulocyte infiltration in response SP is mediated by leukotriene (LT) B₄ derived from mast cells. However, the release of LTB₄ has not been detected using mast cells isolated from human skin. Here we report the release of LTB₄, prostaglandin (PG) D₂ and histamine from guinea pig skin tissue in response to SP. The release of these agents occurred in a dose-dependent manner over a concentration range of SP from 1 × 10^–6 to 3 × 10^–4 M. No detectable PGE₂ was released at any concentration up to 3 × 10^–4 M SP. The kinetics of histamine release induced in response to SP was more rapid than that induced by antigen. By comparison, SP-induced and antigen-induced release of LTB₄ and PGD₂ were similar, but slower than the histamine release. In the absence of extracellular Ca²⁺, release of histamine and PGD₂ in response to SP was partially impaired, but to a lesser extent than that induced by antigen. On the other hand, LTB₄ release in response to both SP and antigen was abolished under the same conditions. These results indicate that SP induces the release of LTB₄, as well as histamine and PGD₂, in the skin most likely from mast cells by a mechanism which may be different from that of mediator release in response to antigen. Received: 1 December 1998 / Received after revision: 31 March 1999 / Accepted: 9 April 1999     

Influence of ultraviolet light on itch and flare reactions in human skin induced by histamine and the histamine liberator compound 48/80

The itch and flare responses induced by intradermal injection of histamine and the histamine liberator compound 48/80 were studied in healthy volunteers before and after exposure to UVB, UVA or PUVA administered 2-3 times weekly for 4 weeks. All three modalities were found to inhibit the responses induced by compound 48/80. The degree of tanning was most pronounced after PUVA and weakest after UVB, without any correlation between tanning and inhibition of itch. In contrast, when induced by histamine, the responses were not inhibited to the same extent, pronounced and significant inhibition being observed only for itching in subjects exposed to UVB. It is concluded that UVB, UVA and PUVA all might be of benefit in treating pruritic states if histamine release is involved and that UVB might have an additional effect by inducing hyposensitivity to itching stimuli.     

Influence of grenz rays and psychological factors on experimental pruritus induced by histamine and compound 48/80

Summary The interaction between grenz rays and experimentally induced pruritus was evaluated in 14 healthy subjects. Grenz rays were administered once weekly for 4 weeks on restricted areas of the upper arms. Pruritus was evoked by intradermal injection of histamine and the histamine liberator compound 48/80. The results were compared with unconditioned values and with those obtained following a placebo treatment procedure. The influence of psychosocial and psychosomatic factors was also evaluated. Grenz-ray therapy reduced itch but not flare responses. The influence of grenz rays was, however, not statistically different from that observed after placebo treatment. Psychosocial and psychosomatic factors were good predictors of individual skin responsiveness. The results indicate that grenz rays do not interfere with experimental histamine-induced pruritus more than placebo and emphasize the importance of knowing individual characteristics and coping strategies.     

Patients' perception of itch induced by histamine, compound 48/80 and wool fibres in atopic dermatitis.

Itch and flare responses were investigated in 32 patients with atopic dermatitis (AD) and in 32 healthy controls. Itch was induced chemically by intradermal injections of histamine (1, 3.3, 10 and 100 micrograms/ml) and compound 48/80 (10 micrograms/ml) into non-lesional skin and mechanically by wearing a woollen sweater. Continuous recording of itch intensity allowed the calculation of itch duration (ID), maximal itch intensity (Imax) and a "total itch index" (Tii). The itch responses were significantly increased in AD patients compared with controls for wool fibres and one of the histamine concentrations (10 micrograms/ml), but not for the remaining three histamine concentrations or compound 48/80. Conversely, the flare response was significantly smaller in AD patients than in controls for the two strongest histamine solutions and compound 48/80. Significant dose-response relationships were found between histamine concentration and each of ID, Imax, Tii and flare in both patients and controls. The slope of the flare-regression line was significantly steeper in controls than in AD patients, whereas the slopes of the itch-regression lines did not differ significantly between the two groups, i.e. their ability to discriminate between weak and strong histamine concentrations did not differ significantly. No increased skin mast cell releasability in vivo to compound 48/80 was shown in AD patients compared with controls. The itch and flare responses of AD patients did not correlate significantly with clinical itch intensity, eczema score or serum IgE level.     

Inhibitory effects of oral prednisolone and fexofenadine on skin responses by prick tests with histamine and compound 48/80

The prick test is a useful skin test for diagnosing immediate hypersensitivity response. Sometimes it is necessary to perform prick tests on patients who have already received antihistamines or corticosteroids. It is, however, occasionally uncertain whether the results of prick tests are reliable. In this study, the inhibitory effects of prednisolone (10 mg/day) and fexofenadine (120 mg/day) on the response to prick tests induced with histamine and compound 48/80 were examined. During a 7-day-continual drug administration, prick tests were performed 8 h after drug administration. The inhibitory effects of fexofenadine on both the histamine- and compound 48/80-induced skin responses were exhibited on the 1st day and persisted from 24 to 36 h after the final administration. The histamine-induced wheal responses were not inhibited by prednisolone, while the compound 48/80-induced flare and wheal responses were significantly inhibited on the 5th day of drug administration. These responses returned to the baseline level 24 h after the last drug administration. Thus, the results of skin tests performed during administration of antihistamines and corticosteroids should be carefully interpreted.     

Effect of captopril on the vascular permeability changes induced by C5a, histamine and compound 48/80

The modulating effect of captopril, an inhibitor of angiotensin-converting enzyme, on the vascular permeability changes induced by intradermal injections of C5a, histamine and compound 48/80, was evaluated in guinea-pigs. Cutaneous vascular permeability changes were measured by the extravasation of intravenously injected 125I-bovine serum albumin. Intraperitoneal injection of 12.5, 25, or 50 mg/kg of captopril 30 min prior to the injection of C5a (10(-11) mol) significantly enhanced the increase in vascular permeability induced by this agent (P less than 0.02). This may be explained by the known property of captopril as an inhibitor of carboxypeptidase. No effect was observed when captopril was injected either 2 or 4 h before the injection of C5a. In contrast, the same doses of captopril, when injected intraperitoneally 2 h before the injection of histamine (10(-8) mol) or compound 48/80 (10 micrograms), significantly suppressed the increase in vascular permeability induced by these agents (P less than 0.02). This suppressive effect occurred in a captopril dose-dependent manner. The ability of captopril to modulate the vascular permeability response induced by vasoactive agents indicates that it is a potentially useful tool to dissect the relative roles of mediators involved in inflammatory processes.     

Epidermal hyperplasia induced in guinea pig flank skin by intradermal injection of Sudan red.

Studies of dermal-epidermal interactions were conducted with guinea pig flank skin and intradermal injections of the irritant, Sudan IV dye in olive oil. These injections led to epidermal hyperplasia in areas overlying the irritant and the effect was most significant when the irritant was placed in the upper dermis. Basal cell mitotic activity and thymidine uptake reached a peak by 24 h and thereafter dropped rapidly. Maximal epidermal thickness (4.3 times the control) resulting from an increase in cell number occurred within 2-4 days. Despite the very short period of increased cell growth, epidermal thickness returned to control values only after a 24-day period. A similar growth response could not be induced by saline injections. A single topical application of the irritant showed a qualitatively and quantitatively different epidermal response. These experiments indicate that an intradermal irritant can lead to epidermal hyperplasia and a long-lasting epidermal thickening.     

The effect of 8-methoxypsoralen plus long-wave ultraviolet (PUVA) radiation on mast cells: PUVA suppresses degranulation of mouse skin mast cells induced by compound 48/80 or concanavalin A

In order to see whether 8-methoxypsoralen (8-MOP) plus long-wave ultraviolet (UVA) radiation (PUVA) has an influence on immediate-type skin reactions, we have undertaken an animal study. Ears of mice were treated with a 0.5% 8-MOP solution topically plus UVA radiation (1.5-2.5 J/cm2). After PUVA radiation, skin responses to intradermal injection with mast cell liberators, including compound 48/80 (2.5 mg/ml, 10 microliter) and concanavalin A (Con-A) (2.0 mg/ml), or with a mixture of 5-hydroxytryptamine (5-HT) and histamine as vasodilator (1.0 mg/ml and 50 mM, respectively) were examined with time (2 h-14 days). At each time point, an ear swelling response (ESR) was measured with a dial thickness gauge. The rate of mast cell degranulation and mast cell numbers were assessed by light microscopy using toluidine blue-stained semithin (1 micron) sections. ESR induced by compound 48/80 or Con-A was significantly suppressed dose-dependently (greater than 42% inhibition) by PUVA between 2 h-3 days postirradiation as compared with that in nonirradiated control mice, and the value returned to normal levels by 7-14 days. Compound 48/80- or Con-A-induced mast cell degranulation (%) was remarkably decreased between 2 h-3 days (greater than 48% inhibition) in accordance with the suppression in ESR and it was restored to the rates in nonirradiated controls by 7-14 days. Neither ESR nor percent degranulation was affected by UVA radiation only (less than 3.5 J/cm2) or application of 8-MOP only. 5-HT plus histamine-mediated ESR was not altered at all by PUVA throughout the experimental period. Since PUVA radiation itself at given doses did not produce measurable ESR, mast cell degranulation, or a reduction in mast cell numbers, and since PUVA did not affect a normal vascular response to vasodilator, it seemed that decreased skin reactivity to mast cell degranulators by PUVA might be due to a PUVA-induced noncytolytic alteration in mast cell release mechanisms.