Dietary docosahexaenoic acid suppresses inflammation and immunoresponses in contact hypersensitivity reaction in mice

This study was designed to examine the immunomodulatory effects of dietary docosahexaenoic acid (DHA) in the absence of eicosapentaenoic acid (EPA). We investigated the effects of feeding dietary DHA ethyl ester (DHA-Et) (97% pure) at levels of 4.8 wt% of the total diet and of feeding EPA ethyl ester (EPA-Et) (99% pure) at 4.8 wt% on the inflammatory response in the challenge phase of the contact hypersensitivity reaction (CHR) in the ears of mice sensitized with 2,4-dinitro-1-fluorobenzene (DNFB). The effect of DHA-Et on T lymphocytes at the CHR site was examined using anti-CD4 antibodies. Furthermore, we examined the cytokines formed at the CHR site on the mRNA level. It was found that 24 h after the challenge, DHA-Et but not EPA-Et reduced the ear swelling. Infiltration of inflammatory cells, in particular, CD4-positive T lymphocytes, into the ears in the challenge phase of CHR was observed. DHA-Et reduced the infiltration of CD4-positive T lymphocytes into the ears. DHA-Et also decreased the expression of interferon-gamma, interleukin (IL)-6, IL-1beta, and IL-2 mRNA in ears. These observations suggest that DHA, but not EPA, may exert an antiinflammatory and immunosuppressive effect. The immunosuppressive effectiveness of fish oil may be attributed mainly to DHA.

Deficiency of IL-2 or IL-6 reduces lymphocyte proliferation, but only IL-6 deficiency decreases the contact hypersensitivity response

We evaluated the importance of IL-2 and IL-6 in primary antigen-induced proliferation of lymph node cells (LNC) and the induction of contact hypersensitivity (CH). These responses were examined in cytokine-deficient mice following application of the contact sensitizer, oxazolone (OX). Proliferation and induction of IL-6 by LNC from IL-2-deficient (IL-2(-/-)) mice were reduced by approximately 95 %, relative to the proliferation of LNC from IL-2(+/+) mice, although induction and elicitation of CH responses was not significantly affected. In contrast, the proliferation of LNC from sensitized IL-6(- /-) mice was reduced by approximately 50% and the CH response was significantly reduced, relative to responses of IL-6(+/+) mice. Although nonspecific inflammatory responses induced by croton oil were similar in IL-6(+/+) and IL-6(-/-) mice, both the acute inflammatory response to OX and the second phase of the inflammatory response were significantly reduced. Thus IL-2 and IL-6 play a significant role in the total proliferative response of LNC following primary contact sensitization. However, the proliferation they promote is not critical for priming the antigen-specific effector cells responsible for eliciting CH responses and IL-6 appears to be more important for expression of the later phases of acute inflammation and the CH induced by OX.

Tumor necrosis factor-alpha impairs contact hypersensitivity induction after ultraviolet B radiation via TNF-receptor 2 (p75)

Acute, low dose ultraviolet B radiation (UVR) impairs induction of contact hypersensitivity (CH) in genetically susceptible mice. Polymorphic alleles at the TNF-alpha locus dictate the susceptibility phenotype, and neutralizing anti-TNF-alpha antibodies restore CH induction in mice exposed to UVR. This circumstantial evidence strongly implicates TNF-alpha in the pathogenesis of failed CH induction after UVR. Using mice genetically deficient in TNF-receptor 1 (p55) or TNF-receptor 2 (p75), we now report that the capacity of TNF-alpha to impair CH induction after UVR required signaling via TNF-receptor 2, rather than TNF-receptor 1. Moreover, acting via the same receptor, TNF-alpha altered the density and morphology of class II MHC-bearing epidermal Langerhans cells. However, UVR retained its capacity to induce tolerance in both TNF-receptor 1 and TNF-receptor 2 deficient mice, indicating that TNF-alpha plays no role in the systemic immune deficit created by UVR.

Measurement of in vivo sunscreen immune protection factors in humans

This study investigates the level of protection provided by sunscreens against solar-simulated UV radiation-induced immunosuppression in humans. The in vivo immune protection factors (IPF) of two broad-spectrum sunscreens were determined by assessing their ability to prevent UV-induced suppression of nickel contact hypersensitivity (CHS) in 15 nickel-allergic volunteers. Each volunteer was irradiated on unprotected skin of the back with different doses of UV daily for 4 days. Multiples of these UV doses were concurrently delivered to sunscreen-treated sites on the contralateral back. Nickel patches were then applied to both irradiated sites and adjacent, unirradiated control sites. Nickel-induced erythema at each site was measured 72 h later with a reflectance spectrometer. Comparison of the nickel reactions of irradiated and unirradiated skin revealed linear UV dose-responses for immunosuppression in both unprotected and sunscreen-treated skin. The minimum level of immunosuppression that can be reliably detected with this method is 20%. Therefore, the UV dose that reduces mean nickel CHS by 20% is the minimal immune suppression dose (MISD). Sunscreen IPF were determined by dividing the mean MISD of sunscreen-treated skin by that of unprotected skin. The sunscreens, with sun protection factors of 9 and 24, had IPF of 6.5 and > 25, respectively.

Local ultraviolet B irradiation impairs contact hypersensitivity induction by triggering release of tumor necrosis factor-alpha from mast cells. Involvement of mast cells and Langerhans cells in susceptibility to ultraviolet B

Our laboratory has previously demonstrated that ultraviolet B radiation impairs contact hypersensitivity induction in ultraviolet B susceptible mice through a tumor necrosis factor-alpha-dependent mechanism, involving calcitonin gene related peptide and cutaneous mast cells. This study was designed to test directly whether mast cells are the source of tumor necrosis factor-alpha, to account for the ultra-violet B-susceptible phenotype. As dermal mast cells seem to release tumor necrosis factor-alpha following exposure to ultraviolet B, we investigated whether tumor necrosis factor-alpha released by mast cells could mediate impairment of contact hypersensitivity in a manner similar to that found with ultraviolet B radiation treatment. First, we loaded Fcepsilon receptors of mast cells of ultraviolet B-susceptible (C3H/HeN), ultraviolet B-resistant (C3H/HeJ), and mast-cell deficient (Sl/Sld) mice by intradermal injections of anti-dinitrophenyl immunoglobulin E antibodies. Twenty-four hours later, dinitrophenyl was injected intravenously, and within 30 min oxazolone was painted on injected skin sites. Contact hypersensitivity induction was impaired in ultraviolet B-susceptible mice, but not in ultraviolet B-resistant or Sl/Sld mice, and treatment with anti-tumor necrosis factor-alpha antibodies was able to reverse this impairment of contact hypersensitivity. Second, we have found that ultraviolet B radiation did not impair contact hypersensitivity induction when haptens were painted on irradiated skin of mast cell deficient mice. As ultraviolet B radiation impairs contact hypersensitivity induction through a tumor necrosis factor-alpha-dependent mechanism, we conclude that ultraviolet B radiation triggers the prompt release of tumor necrosis factor-alpha from dermal mast cells, and that mast cell-derived tumor necrosis factor-alpha interferes with generation of the hapten-specific signal required for contact hypersensitivity induction. In addition, we are providing data that indicate that tumor necrosis factor-alpha levels released from mast cells as well as sensitivity of Langerhans cells to tumor necrosis factor-alpha contribute in defining the phenotypes of resistance versus sensitivity to ultra-violet B radiation.

A critical role for dermal mast cells in cis-urocanic acid-induced systemic suppression of contact hypersensitivity responses in mice

Many studies have implicated cis-urocanic acid (cis-UCA) in UVB-induced immunomodulation. The strongest evidence came from studies in mice whereby a cis-UCA antibody blocked UVB-induced suppression of delayed-type hypersensitivity responses. Furthermore, in several studies, the cis-UCA antibody at least partially reversed UVB suppression of contact hypersensitivity responses. Previous reports suggested that cis-UCA was immunomodulatory through its effects on keratinocytes, Langerhans cells, fibroblasts, T lymphocytes, natural killer cells and monocytes/macrophages. As dermal mast cells were recently demonstrated to be critical to UVB-induced systemic suppression of certain delayed-type and contact hypersensitivity responses, we investigated whether they were involved in the processes by which cis-UCA was immunomodulatory. Not only was there a correlation between dermal mast cell prevalence and the degree of susceptibility of different strains of mice to the immunomodulatory effects of cis-UCA, there was also a functional link. Mast cell-depleted Wf/Wf mice were rendered susceptible to immunomodulation by cis-UCA injected subcutaneously only after their dorsal skin had been reconstituted with bone marrow-derived mast cell precursors. These studies suggest that mast cells are critical to the processes by which cis-UCA suppresses systemic contact hypersensitivity responses to the hapten, trinitrochlorobenzene, in mice.

Antioxidant protection from solar-simulated radiation-induced suppression of contact hypersensitivity to the recall antigen nickel sulfate in human skin

Solar radiation induces suppression of the local effector mechanisms involved in immune responses to recall antigens. By using a low-dose solar-simulated radiation protocol, we investigated whether oral supplementation of the antioxidants RRR-alpha-tocopherol combined with L-ascorbic acid prevented radiation-induced suppression of the contact hypersensitivity response to nickel sulfate. In a prospective, randomized study, nickel-sensitive individuals were given RRR-alpha-tocopherol 2 g/d oral supplements combined with L-ascorbic acid 3 g/d for 50 d (group 1). Individuals in the control group were given a placebo (group 2). The reaction to a standardized patch test with serial dilutions of nickel sulfate and the irritant skin reaction to sodium lauryl sulfate were assessed by visual grading and by reflectance spectrophotometry in radiation-exposed and nonexposed skin 50 days after supplementation. Results showed that the contact hypersensitivity response to the recall antigen nickel sulfate was significantly suppressed in the radiation-exposed skin of those who took the placebo. Supplementation with RRR-alpha-tocopherol combined with L-ascorbic acid significantly protected against the radiation-induced suppression of the contact hypersensitivity response to nickel sulfate. The irritant reaction to sodium lauryl sulfate was not suppressed by radiation, and antioxidant supplementation did not modulate this response. In conclusion, a combination therapy of systemic high-dose RRR-alpha-tocopherol combined with L-ascorbic acid prevented solar-simulated radiation-induced suppression of the local immune response to the recall antigen nickel sulfate in human skin. This immunoprotective effect of combined RRR-alpha-tocopherol and L-ascorbic acid could be exploited for the prevention of solar radiation-induced skin cancer in an antioxidant intervention study.

[Prevention of allergy by protective skin creams: possibilities and limits]

Despite promising efficacy data for protective creams and many scientifically proven advances that have been achieved concerning the prevention of irritative contact dermatitis, protection against sensitising substances remains a particular problem due to the minimal amounts of allergen that trigger allergic contact dermatitis. Therefore, specific allergen-blocking substances have been tested which are designed to prevent sensitising processes and in particular avoid occurrence of contact dermatitis in already sensitised individuals. In this review, we present the results of current studies mainly focussed on preventing occupational contact dermatitis caused by metal salts, using different chelating agents. In the United States allergic contact dermatitis is often due to strongly sensitising plant allergens of Toxicodendron species, a factor of importance in outdoor professions. Therefore, attempts have been made to use linoleic acid dimers and organoclay materials such as quaternium-18 bentonite for prophylaxis in topical treatments. Most studies investigate effectiveness against experimentally induced allergic contact dermatitis in sensitised volunteers using standardised allergen extracts. Although several preparations showed some benefit by possibly preventing certain quantities of allergen from penetrating the epidermis, further effort will be required before sufficient protective creams with allergen-blocking properties are available for workplaces.

Protection against UV-induced systemic immunosuppression in mice by a single topical application of the antioxidant vitamins C and E

PURPOSE

Reactive oxygen species are involved in UV-induced suppression of the immune system. Topical treatment with the antioxidant vitamins C (L-ascorbic acid, ASC) and E (D-alpha-tocopherol, TOC) can support the endogenous antioxidant defence system and prevent immunosuppression.

MATERIALS AND METHODS

Mice were topically treated with a single dose of ASC, TOC or a combination and irradiated with UVB. Then systemic immunosuppression was measured using a model based on the induction of a contact hypersensitivity response to dinitrofluorobenzene. To investigate the mechanism of protection, cis-urocanic acid-induced immunosuppression was investigated in a different contact hypersensitivity model measuring local immunosuppression. The levels of ASC and TOC in the epidermis were determined by HPLC.

RESULTS

Both ASC and TOC prevented UV-induced suppression of the contact hypersensitivity response. TOC was effective at doses of 2.5 to 10 nmol/cm2 and ASC at 0.5 to 5 micromol/cm2. At the highest dose, the response in the ASC-treated mice was no longer significantly different from that in the positive control group. Contrary to expectations, combinations of the two compounds did not provide additional protection. The experiments with ASC or TOC against immunosuppression by cis-urocanic acid also yielded protection, but this was less efficient than against UV. The concentrations of ASC and TOC in the epidermis were so low that UVB absorption could be excluded as the cause of the protection.

CONCLUSIONS

ASC and TOC can be used to prevent systemic UV-induced immunosuppression. They are effective at relatively low doses after a single topical application prior to the irradiation.

Improvement in skin barrier function in patients with atopic dermatitis after treatment with a moisturizing cream (Canoderm)

Patients with atopic skin show a defective barrier function both in rough and in clinically normal skin, with an increasing risk of developing contact dermatitis. Moisturizing creams are often used in the treatment of dry skin. The purpose of this study was to investigate the influence of treatment with a urea-containing moisturizer on the barrier properties of atopic skin. Fifteen patients with atopic dermatitis treated one of their forearms twice daily for 20 days with a moisturizing cream. Skin capacitance and transepidermal water loss (TEWL) were measured at the start of the study and after 10 and 20 days. On day 21 the skin was exposed to sodium lauryl sulphate (SLS) and on day 22 the irritant reaction was measured non-invasively. Skin capacitance was significantly increased by the treatment, indicating increased skin hydration. The water barrier function, as reflected by TEWL values, tended to improve (P = 0.07), and the skin susceptibility to SLS was significantly reduced, as measured by TEWL and superficial skin blood flow (P < 0.05). Thus, it seems that certain moisturizers could improve skin barrier function in atopics and reduce skin susceptibility to irritants. The mechanism and the clinical relevance need further investigation.

The anatomic site of photodynamic therapy is a determinant for immunosuppression in a murine model

The role of the irradiation site in the induction of suppression of the contact hypersensitivity (CHS) response following photodynamic therapy (PDT) was examined in a murine model. Laser irradiation on the flanks of nontumor-bearing Photofrin-injected mice caused suppression of the CHS response. If the irradiation was conducted on a subcutaneously implanted foil disc on the flank no immunosuppression occurred, indicating that no suppressive factor(s) of sufficient quantity to cause suppression was released from the skin, but rather irradiation of internal organs was the cause. Irradiation of tumors implanted on the flanks of mice reduced the suppression, suggesting an immunopotentiating effect of PDT. Irradiation on the thigh in the presence or absence of a tumor gave no immunosuppression. These results suggest that the anatomic site of irradiation is one determinant for the elicitation of suppression of the CHS response.

Several different ion channel modulators abrogate contact hypersensitivity in mice

A major obstacle in transdermal delivery of drugs is the development of adverse skin sensitization reactions. We tested the concept that ion channel modulators as a class of agents suppress contact hypersensitivity in a mouse model. Mice were sensitized to several contact sensitizing chemicals including dinitrochlorobenzene (DNCB) and a sensitizing drug, nadolol. We report our successful use of several ion channel modulators in suppressing contact hypersensitivity, including amiloride, ethacrynic acid (ECA), nifedipine and verapamil. For this purpose, Balb/c female mice were sensitized with DNCB, and abrogation of induction of contact hypersensitivity reaction (CHR) was examined by topical pretreatment of the target-sensitized skin with amiloride, nifedipine and pairwise combinations of these agents with ECA, a potassium ion channel blocker. Abrogation of induction of CHR was observed in all cases. In addition, suppression of contact hypersensitivity was observed in nadolol-sensitized mice pretreated with either verapamil or nifedipine. The results indicate that ion channel inhibitors are broadly effective inhibitors of allergic contact dermatitis and may be useful for facilitating the transdermal delivery of therapeutic drugs that have sensitization potential.

cis-urocanic acid induces mast cell degranulation and release of preformed TNF-alpha: A possible mechanism linking UVB and cis-urocanic acid to immunosuppression of contact hypersensitivity

The search for effective inhibitors of transdermal drug-induced contact sensitization was directed to dermal mast-cell-degranulating agents (MCDA). Human skin organ cultures were employed to test whether cis-urocanic acid (C-UA) and other potential MCDAs cause mast cell degranulation. These were then tested for their ability to inhibit the induction phase of the contact hypersensitivity reaction (CHR). C-UA at 1 microg/ml significantly depleted mast cell chymase, whereas trans-urocanic acid (T-UA) was relatively ineffective. C-UA, but not T-UA, induced local effects of liberated mast cell TNF-alpha, as detected by E-selectin expression on the microvascular dermal endothelium. C-UA significantly reduced (>70%) the ear swelling response in Balb/c mice, when applied 24 h prior to application of a sensitizing amount of dinitrochlorobenzene (DNCB), and induced a prolonged (>3 weeks) state of immune tolerance (>40%). Similar effects on local immunosuppression of CHR were observed with topical chloroquine and capsaicin, while cromolyn, a mast cell membrane stabilizer, was unable to inhibit DNCB-induced CHR. It is suggested that MCDAs may interfere with downstream events associated with accessory cell function.

Photoprotection: sunscreens and the immunomodulatory effects of UV irradiation

UV-B irradiation (UVR) of the host, in both humans and animal models, induces dose-related acute and chronic changes in skin which include erythema and photoageing, and induction of cancer. It can also induce modulation of immune responses of the host to antigens presented following irradiation. Commercially-available, broad-spectrum, high SPF (15, 15 + ) sunscreens protect against most effects of UV irradiation. An exception is the effects of UVR on immune responsiveness, with varying degrees of protection having been reported. We examined a system of UV-induced systemic suppression of contact hypersensitivity (CHS) responses in BALB/c mice. A range of commercially-available, broad spectrum, high SPF (15 + ) sunscreens demonstrated at best partial protection against systemic immunosuppression, yet were able to protect against two hallmarks of acute UVR-induced damage: skin oedema and keratinocyte proliferation. Two major models have been identified for the induction of immunosuppression following UVR, one identifying trans-urocanic acid (trans-UCA; deaminated histidine, located in the stratum corneum) as the critical photoreceptor, the other featuring DNA. UVR of trans-UCA produces cis-UCA, which itself is immunomodulatory. There was some abrogation of trans to cis isomerisation of urocanic acid in UV-irradiated, sunscreen-protected mice. However, the majority of the immunomodulation seen in these mice was abrogated by pretreatment with a monoclonal antibody to cis-urocanic acid. It is possible to induce formation of cis-urocanic acid in BALB/c skin in the absence of immunosuppression, using lower doses of UV radiation, indicating that formation of cis-urocanic acid in the stratum corneum is not necessarily sufficient to induce immunosuppression in the UV-irradiated host. The mechanisms of induction of the immunomodulated state in the UV-irradiated host are potentially diverse and the subject of ongoing debate. Our studies maintain a role for cis-UCA, and form the basis for further studies on its involvement in immunomodulation by UVR in sunscreen-protected hosts.

The effects of two UVB radiation-absorbing sunscreens on UV radiation-induced carcinogenesis, suppression of the contact hypersensitivity response and histological changes in the hairless mouse

The research summarised in this report suggests that the two UVB-absorbers, o-PABA and 2-EHMC, have different modes of protection against UV radiation-induced immunosuppression, carcinogenesis and histological alterations, that appear to be independent of their SPF values, within experimental limits. The UVB-absorber o-PABA appears offer a valuable level of protection against photocarcinogenesis.

Inhibitory effect of cycloartenol ferulate, a component of rice bran, on tumor promotion in two-stage carcinogenesis in mouse skin

Inhibitory activity against 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced inflammation in mice was observed in the methanol extract of rice bran and gamma-oryzanol. The active components of rice bran, sitosterol ferulate, 24-methylcholesterol ferulate, cycloartenol ferulate and 24-methylenecycloartanol ferulate inhibited markedly the TPA-induced inflammation in mice. The 50% inhibitory dose of these compounds for TPA-induced inflammation was 0.2-0.3 mg/ear. Furthermore, cycloartenol ferulate markedly inhibited the tumor-promoting effect of TPA in 7,12-dimethylbenz[a]anthracene-initiated mice.

[Ketoprofen-induced contact photosensitivity disorders: 5 cases]

BACKGROUND

Nonsteroidal antiinflammatory drugs (NSAID) are widely used in topical applications for benign diseases. Adverse skin reactions include contact eczema and photocontact dermatitis. Among the NSAID used in topical applications, arylpropionic derivatives, notably ketoprofen, are frequently implicated.

CASE REPORTS

We observed 5 patients who developed eczema lesions after application of Ketum, a gel containing ketoprofen used on healthy skin after exposure to sunlight. Photoallergy explorations evidenced positive photopatch-tests for ketoprofen with UVA and total light. The anamnesis suggested a photoallergic mechanism which was confirmed by histological examination of the biopsy of a UVA positive photopatch-test and by negative photopatch-tests in 10 healthy controls.

DISCUSSION

The photosensitizing potential of ketoprofen in the UVA spectrum is well known. Although the number of adverse reactions is quite small compared with widespread use, physicians should be aware of this photosensitivity and report all cases to the pharmacovigilance center.

Glutathione ethylester protects against local and systemic suppression of contact hypersensitivity induced by ultraviolet B radiation in mice

Irradiation of the skin with ultraviolet B (UVB) radiation causes a local and systemic suppression of T-cell-mediated immune responses. Recently, N-acetylcysteine was found to protect against UVB-radiation-induced immunosuppression and several other types of damage induced by UV radiation. The protective effects appeared to be caused by an increase in glutathione (GSH). This increase was limited by feedback inhibition by GSH of its own synthesis. Better results were expected with the use of GSH derivatives which do not require de novo synthesis, such as GSH esters. In this study, topical application of glutathione ethylester (GSH-Et) was found to increase the epidermal GSH level in mice in a manner that was dependent on dose to 1234% of the control value at the highest dose tested (2.0 micromol/cm2). This resulted in dose-dependent protection against UVB-radiation-induced suppression of contact hypersensitivity. The highest dose of GSH-Et tested provided 83% protection against local suppression and 62% protection against systemic suppression. Immunosuppression induced by topically applied cis-urocanic acid (cis-UCA) was prevented completely. Although an effect on the formation of pyrimidine dimers cannot be excluded, the protective effect of GSH-Et seems to be mediated through inhibition of the action of cis-UCA.

Amended economic impact analysis of final rule requiring use of labeling on natural rubber containing devices--FDA. Final rule; amended economic analysis statement

The Food and Drug Administration (FDA) is issuing an amended economic analysis statement relating to a final rule that published in the Federal Register of September 30, 1997 (62 FR 51021), requiring labeling statements concerning the presence of natural rubber latex in medical devices. This rule was issued in response to numerous reports of severe allergic reactions and deaths related to a wide range of medical devices containing natural rubber. The final rule becomes effective on September 30, 1998. In order to allow further comment on the economic impact of the September 30, 1997, final rule, FDA published in the Federal Register of June 1, 1998, an amended economic impact statement, including an amended initial regulatory flexibility analysis (IRFA) that it prepared under the Regulatory Flexibility Act (RFA), as amended by the small Business Regulatory Enforcement and Fairness Act (SBREFA). After considering comments submitted in response to the June 1, 1998, amended economic analysis statement, FDA is issuing the amended final economic impact statement, including an amended final regulatory flexibility analysis.

Natural rubber-containing medical devices; user labeling; cold seal adhesives partial stay--FDA. Final rule

The final rule for user labeling requirements for natural rubber-containing medical devices, 21 CFR 801-437, was published on September 30, 1997, and becomes effective on September 30, 1998. The Food and Drug Administration (FDA) is adding a note to that rule to stay, for 270 days from the effective date, paragraphs (f) and (g) as those final rule requirements relate to device packaging that uses "cold seal" adhesives. Labeling changes required by other paragraphs of this final rule must be incorporated in the labeling of devices distributed after September 30, 1998, even if the devices are packaged in "cold seal" packages. Device packaging that uses natural rubber only on adhesives contained in the flaps of device packaging is not considered subject to the rule. Manufacturers of devices packaged with "cold seal" adhesives may, if necessary, submit a petition for an extension of the 270-day stay.

Ultraviolet B induced suppression of induction of contact sensitivity in human skin is not associated with tumour necrosis factor-alpha-308 or interleukin-10 genetic polymorphisms

Low doses of ultraviolet B (UVB) can induce localized immunosuppression in skin. This effect may be important in the induction of skin cancers and is thought to be mediated by tumour necrosis factor (TNF) alpha and interleukin (IL) 10 in conjunction with other factors. In humans a transition polymorphism in the TNF-alpha gene may affect TNF-alpha secretion and the promoter region of the IL-10 gene contains a CA repeat polymorphism which may affect gene function. We have therefore investigated the association of these polymorphisms with UVB-induced immunosuppression in humans. Volunteers (n = 42) were irradiated with UVB then sensitized on irradiated skin with diphenylcyclopropanone (DPCP) and subsequently antigen challenged with DPCP. DNA was extracted from blood samples and volunteers genotyped for the TNF-alpha polymorphism by polymerase chain reaction (PCR) and restriction digestion. The CA repeat polymorphism was amplified by PCR and sized by gel electrophoresis. Twenty-four volunteers were susceptible to UVB-induced immunosuppression and 18 were resistant. The association of allele frequencies and phenotype was statistically tested using a chi2-test. For both the TNF-alpha and IL-10 polymorphisms, there was no statistically significant association between allele types and response to UVB. These results indicate that variation in the immune response to UVB in humans is not associated with the TNF-alpha-308 transition or IL-10 CA repeat polymorphisms, although other as yet undetected DNA sequence variants of these genes may be involved.

Latex allergy: a strategy for management

Latex is a ubiquitous part of life today. It is a constituent of many household products and medical devices, although not always obvious on examination. The increase in incidence of potentially life-threatening allergic reactions to latex has been a cause for mounting concern over recent years. Although there have been recent reviews of the general problem of latex allergy, there is little advice available to anaesthetists on how to develop an effective strategy to implement within their own hospitals. The aim of this article is to improve awareness of latex allergy and by describing the development of our strategy to identify and safely manage those at risk in the peri-operative period, facilitate the process for other departments.

Cyclosporin A inhibits 12-O-tetradecanoyl-phorbol-13-acetate-induced cutaneous inflammation in severe combined immunodeficient mice that lack functional lymphocytes

A single application of 12-O-tetradecanoyl-phorbol-13-acetate (TPA) to mouse skin results in an acute inflammatory response, with an influx of neutrophils and lymphocytes, epidermal hyperplasia and abnormal keratinocyte differentiation. This response is significantly inhibited by topical cyclosporin A (CyA). Although CyA is known to inhibit T-cell activation, the role of T cells in TPA-induced cutaneous inflammation is not well understood. In this study, we have used severe combined immunodeficient (SCID) mice, which carry a spontaneous mutation resulting in the absence of functional T and B lymphocytes, to examine whether lymphocytes are required for the TPA response in mouse skin and whether CyA inhibits the TPA response in SCID mice. A significant increase in epidermal and deep dermal inflammation was observed in both SCID and CB-17 mice 24 h after a single application of TPA (10 nmol) compared with vehicle (P < 0.05, n = 5-7). Simultaneous application of CyA (1.7 mumol) plus TPA resulted in a significant reduction in epidermal and deep inflammation at 24 h compared with TPA alone in SCID and CB-17 mice (P < 0.05, n = 7). In contrast to hairless mice, a variable increase in epidermal thickness was observed in both SCID and CB-17 mice after treatment with TPA at 24 and 72 h, which was not significantly affected by CyA. These data indicate that TPA-induced inflammation in mouse skin does not depend on lymphocytes. In addition, the inhibition of TPA-induced epidermal and deep dermal inflammation by CyA in SCID mouse skin suggests that CyA exerts effects on cutaneous inflammation in mice in the absence of functioning T cells.

Do barrier creams and gloves prevent or provoke contact dermatitis?

Barrier creams and gloves play an important role in the prevention of contact dermatitis, and various in vivo and in vitro methods have been developed to investigate their efficacy. However, their actual benefit in the workplace is still being debated. This article reviews both the benefits and adverse effects of barrier creams and gloves.

Effects of SA6541, a leukotriene A4 hydrolase inhibitor, and indomethacin on carrageenan-induced murine dermatitis

We investigated the effects of S-(4-dimethylaminobenzyl)-N-[(2S)-3-mercapto-2-methylpropionyl]-L- cysteine (SA6541), a potent leukotriene A4 hydrolase inhibitor. on early phase of carrageenan-induced dermatitis model. Carrageenan injection induced edema and neutrophil influx in the mouse ear. SA6541 inhibited edema formation and neutrophil influx. SA6541 also inhibited leukotriene B4 production but not prostaglandin E2 production in the mouse ear. On the other hand, indomethacin inhibited edema formation but not neutrophil influx. Indomethacin also inhibited prostaglandin E2 production but not leukotriene B4 production. Combination therapy with SA6541 and indomethacin strongly inhibited edema formation in comparison with treatment with either agent alone. These results suggest that leukotriene B4 may be important in the pathogenesis of dermatitis.

Protection of UV-induced suppression of skin contact hypersensitivity: a common feature of flavonoids after oral administration?

In this study we investigated the effect of the dietary ingredients fruit and vegetable, green tea phenol extract (GTP) and the specific flavonoid components quercetin and chrysin on the UV-induced suppression of the contact hypersensitivity (CHS) response to picryl chloride (PCl). The SKH-1 mice were fed with test diet from 2 or 4 weeks before and during the UV irradiation (daily, 95 mJ/cm2) and tested for the CHS ear-swelling response 10 weeks after the onset of the irradiation. For the CHS, mice were immunized with PCl by epicutaneous application on nonirradiated sites. Four days after sensitization all mice were challenged on both sides of each ear by topical application of one drop PCl. In addition, from mice fed with the fruit and vegetable mixture the number of Langerhans cells (LC) were scored in the skin and from mice fed with quercetin, quercetin levels in plasma were measured at week 11 after the start of UV irradiation. It was found that fruit and vegetable (19% in the diet), GTP (0.1% and 0.01% in the drinking water), quercetin (1% in the diet) and chrysin (1% and 0.1% in the diet), prevented statistically significantly the UV-induced suppression of CHS to PCl. In the skin of mice fed with fruit and vegetables combined with UV irradiation the number of LC were comparable to the control mice, whereas the number of LC were significantly diminished in mice treated with UV only. This protective effect on the presence of LC in the epidermis after UV irradiation, which was also observed in a previous study with quercetin, may play a role in the prevention of UV-induced immunosuppression by the flavonoids tested. In conclusion, we found protection of flavonoids against UV-induced effects on CHS, which may be a common feature of most flavonoids.

Effect of vitamin E on contact sensitization responses induced by 2,4-dinitrochlorobenzene in mice

The effect of vitamin E on the contact sensitization responses induced in mice by 2,4-dinitrochlorobenzene (DNCB) was studied. Mice were fed a vitamin E-adequate or a vitamin E-deficient diet for 5 weeks. The amounts of thiobarbituric acid-reactive substances in the spleens and draining auricular lymph nodes of mice were decreased by dietary vitamin E. Dietary vitamin E prevented lipid peroxidation in the spleens and lymph nodes of mice. Contact sensitization develops in two phases, induction (sensitization) and elicitation. Following sensitization to DNCB on ears, draining lymph node responses, i.e., lymph node weight, total lymph node cell number and in vitro lymph node cell proliferation as assessed by [3H]methyl thymidine incorporation, were examined. These responses, activated by DNCB, were lower in the mice fed a vitamin E-deficient diet as compared with those of the mice fed a vitamin E-adequate diet. In the elicitation phase, lymphocytes from sensitized mice respond to the antigen and blastogenate in vitro. The blastogenesis of spleen lymphocytes in the DNCB-sensitized mice was decreased by vitamin E deficiency, which was enhanced by exogenously adding vitamin E. It was found that vitamin E deficiency decreases the contact sensitization responses to DNCB in mice, but responses were restored by exogenous vitamin E. In conclusion, vitamin E may participate in the lymphocyte responses to contact allergens through scavenging reactive oxygen species.

Interleukin 12 breaks ultraviolet light induced immunosuppression by affecting CD8+ rather than CD4+ T cells

Recent studies showed that injection of interleukin (IL)-12 prevents ultraviolet (UV) light mediated suppression of contact hypersensitivity and breaks UV-induced hapten specific tolerance. UV-mediated suppression can be adoptively transferred by injecting splenocytes from UV-irradiated mice; however, suppression is not transferable when donor mice are treated with IL-12 after UV-irradiation. This study was performed to elucidate the mechanisms by which IL-12 counteracts this immunosuppression. To characterize the cells transferring suppression, depletion studies were performed revealing that UV-induced suppression is transferred via CD8+ T cells. To investigate whether IL-12 counteracts UV-induced suppression by either inhibiting the development of CD8+ suppressor T cells or inducing CD4+ effector T cells, splenocytes from mice, which were IL-12 treated and sensitized through UV-exposed skin, were depleted from CD4+ T cells and transferred into naive mice that were subsequently sensitized. Whereas transfer of splenocytes from UV-irradiated mice inhibited sensitization of recipients, no inhibition was observed after transfer of splenocytes from UV-exposed and IL-12 treated mice. Recipients that received CD4 depleted spleen cells from UV-exposed and IL-12 treated donors, were still fully sensitizable. IL-12 also blocked transfer of UV-induced suppression when it was injected into UV-exposed donor animals at a time point when suppressor cells had already developed. CD4 depletion of such splenocytes did not result in a loss of the reconstitutive effect of IL-12. This suggests that IL-12 may break UV-induced tolerance not by inducing CD4+ effector T cells, but rather by inhibiting or inactivating suppressor T cells belonging to the CD8 subtype.

Implementation recommendations for making health care facilities latex safe

The problem of latex allergy is not limited to health care workers who provide direct patient care. Individuals in environmental services, dietary, engineering, and medical records departments have the potential for sensitization. Due to the significant liability that may arise from a latex-induced anaphylaxis or death, it is no longer prudent for health care facilities to ignore the problem. This article proposes practical recommendations for implementation of an institution wide latex-safe environment in health care facilities.

Epidemiology of contact dermatitis. The information network of departments of dermatology (IVDK) in Germany

In 1988, the multicenter project "Information Network of Departments of Dermatology (IVDK)", including eight university skin hospitals was founded. It now comprises 30 participating centers. At these centers, all patch test results are recorded, together with important anamnestic details and, twice a year, these are sent to the data center at the Göttingen University Skin Hospital. Regular, descriptive analyses of data collected by this epidemiological surveillance system serve the different purposes discussed in this paper: 1) observation of "sentinel events"; e.g. an increase in the proportion of patients tested who were sensitized to a certain allergen, or the identification of certain subgroups at particular risk as a starting point for further research or preventive action, and 2) advancement of good clinical practice in patch testing. In October 1996, a working group of the European Society of Contact Dermatitis (ESCD) called the "European Surveillance System on Contact Allergies (ESSCA)" was established with a similar aim of communal data collection and analysis.

Genetic variation in low-dose UV-induced suppression of contact hypersensitivity and in the skin photocarcinogenesis response

Two of the major cutaneous consequences of ultraviolet (UV) radiation exposure are immunosuppression and the development of skin cancer. This study examined whether these effects are genetically determined. Suppression of contact hypersensitivity by local, low-dose UV radiation was examined in what have been termed "UV-susceptible" and "UV-resistant" strains of mice. C3H/HeJ mice ("UV resistant") were resistant to the adverse effects of low-dose UV radiation when normal doses of hapten were applied to UV-irradiated skin; however, they were sensitive when the amount of hapten used for sensitization was reduced. A similar effect was observed in BALB/c mice ("UV resistant") and when the hapten was dimethylbenz(a)anthracene, thus indicating that the genetic variation was not strain or hapten specific. Despite the fact that some strains were sensitive and some were resistant to low-dose UV radiation when high doses of hapten were employed, all strains initially sensitized to hapten through UV-irradiated skin were found to be unresponsive when rechallenged on normal skin, no matter what the initial sensitizing dose of hapten was. To determine whether other biologic effects of UV also exhibited genetic variation, C3H/HeN and C3H/HeJ mice were compared for susceptibility to UVB-induced skin cancer formation. C3H/HeJ mice developed significantly more tumors than C3H/HeN mice when subjected to a single dose of UV radiation followed by repeated exposure to the tumor promoter 12-O-tetradecanoyl-phorbol-13-acetate. These studies provide strong evidence that genetic factors influence individual susceptibility to the biologic effects of UV radiation.

Alpha hydroxyacids modulate stratum corneum barrier function

Alpha hydroxyacids (AHAs) are used to enhance stratum corneum desquamation and improve skin appearance. The purpose of this study was to evaluate whether some AHAs improve skin barrier function and prevent skin irritation. Eleven healthy subjects (aged 28 +/- 6 years, mean +/- SD) entered the study. Six test sites of 8 x 5 cm (four different AHAs, vehicle only (VE) and untreated control (UNT) were selected and randomly rotated on the volar arm and forearm. The four different AHAs at 8% concentration in base cream were glycolic acid (GA), lactic acid, tartaric acid (TA) and gluconolactone (GLU). The products were applied twice a day for 4 weeks (2 mg/cm2). At week 4, a 5% sodium lauryl sulphate (SLS) challenge patch test was performed under occlusion for 6 h (HillTop chamber, 18 mm wide) on each site. Barrier function and skin irritation were evaluated by means of evaporimetry (Servomed EP-1) and chromametry (a* value, Minolta CR200) weekly, and at 0, 24 and 48 h after SLS patch removal. No significant differences in transepidermal water loss (TEWL) and erythema were observed between the four AHAs at week 4. After SLS challenge, GLU- and TA-treated sites resulted in significantly lower TEWL compared with VE, UNT (P < 0.01) and GA (P < 0.05) both at 24 and 48 h. Similarly, a* values were significantly reduced after irritation in GLU- and TA-treated sites. This study shows that AHAs can modulate stratum corneum barrier function and prevent skin irritation; the effect is not equal for all AHAs, being more marked for the molecules characterized by antioxidant properties.

Worker education in the primary prevention of occupational dermatoses

This paper reports the evaluation of a skin care education programme conducted on a fine chemicals manufacturing site where over 1,000 employees are located. Approximately 60% are involved in chemical manufacture. Over a 12 month period production staff received training in prevention of occupational dermatoses linked to a site-wide poster initiative. The incidence of new cases of occupational dermatoses fell from 0.055 (70 cases in 1,277 employees) to 0.021 (27 cases in 1,277 employees) before and after the intervention respectively (p < 0.0001). After other factors such as chemicals handled, observer bias and changes in reporting related to socioeconomic climate were taken into account it is concluded that this study demonstrates the importance of worker education as a tool for primary prevention of disease. Training materials such as video and poster presentations may be effectively used in the chemical manufacturing industry as an adjunct to prevention and control of exposure to substances hazardous to the skin. Such methods may also be used in other industries where there are significant risks of dermatoses.

Recombinant soluble alphabeta T cell receptors protect T cells from immune suppression: requirement for aggregated multimeric, disulfide-linked alphabeta heterodimers

Recombinant soluble T cell receptors (sTCR) protected contact sensitivity (CS) effector T cells from down-regulation or immunosuppression. CS-protecting sTCR were released enzymatically from the surface of thymoma cells transfected with cDNAs encoding TCR-alpha and -beta extracellular domains that were expressed with a phosphatidylinositol linkage. sTCR affinity purified on anti-TCR-alpha and anti-TCR-beta mAb columns had identical CS-protective activity, as did sTCR from a CD4+ Th2 clone or from a CD8+ cytotoxic clone. Reduced sTCR alpha- and beta-chains had no CS-protective activity, but this was restored when the TCR chains were rejoined into disulfide-linked alphabeta heterodimers. sTCR CS protection was Ag nonspecific, MHC unrestricted, and not influenced by the relevant synthetic peptide specific for the TCR complexed with appropriate MHC. CS protection may have resided in the sTCR constant region. When heated at 62 degrees C for 30 min, sTCR formed a CS-protecting aggregate, with a molecular mass of 481 +/- 37 kDa, corresponding to an alphabeta TCR pentamer. HPLC gel filtration essentially confirmed the molecular mass at 516 kDa for the multimer, while the monomer, which was an alphabeta TCR heterodimer, had an expected molecular mass of approximately 104 kDa and no bioactivity. In summary, the pentameric sTCR may bind to and activate lymphoid cells, perhaps via constant domains, resulting in protection of CS effector T cells from down-regulation. The ability of sTCR to protect CS effector T cells from down-regulation/suppression, if generalized, could overcome immunosuppression accompanying infectious diseases, particularly AIDS, or in tumors.

Immunosuppression induced by acute solar-simulated ultraviolet exposure in humans: prevention by a sunscreen with a sun protection factor of 15 and high UVA protection

BACKGROUND

Cutaneous exposure to UVB radiation impairs the induction of contact hypersensitivity (CHS). Variable results have been found among studies examining the use of sunscreens to prevent UV-induced immunosuppression.

OBJECTIVE

Our purpose was to determine whether solar-simulated exposure of human skin resulted in an impairment of CHS responses and whether the preapplication of an intermediate sun protection factor (SPF) sunscreen could prevent this locally UV-induced immunosuppression.

METHODS

Irritant and CHS responses to dinitrochlorobenzene (DNCB) were randomly assessed in 160 human volunteers with or without UV exposure and with or without prior application of an SPF 15 sunscreen with high UVA protection. DNCB sensitization was performed 3 days after acute UV irradiation corresponding to 3 minimal erythema doses.

RESULTS

After solar-simulated UV exposure, the percentage of positive responses to DNCB sensitization dropped from 95% to 50% (p = 0.003). Prior application of the sunscreen formulation did not modify the percentage of positive responses (90%) and maintained the immunization rate at 85% among volunteers exposed to UV.

CONCLUSION

A localized sunburn can impair the afferent arm of CHS reactions in humans. The use of intermediate SPF sunscreens with high UVA protection adequately protects from the suppression of CHS responses that occurs after acute solar-simulated UV exposure.

Broad-spectrum sunscreens provide greater protection against ultraviolet-radiation-induced suppression of contact hypersensitivity to a recall antigen in humans

This study investigates the extent to which sunscreens protect humans from ultraviolet (UV)-radiation-induced immunosuppression. In the presence of solar-simulated UV, three sunscreens with differing UVA transmission were assessed for their ability to protect the contact hypersensitivity (CHS) response to nickel of 16 nickel-allergic subjects. The sunscreens contained 2-ethylhexyl para-methoxycinnamate (cinnamate), cinnamate with oxybenzone, or cinnamate with zinc oxide, respectively. All had sun protection factors of 10 and hence inhibited UV erythema to similar extents. Volunteers were irradiated on their backs with suberythemal UV daily for 5 d after application of the sunscreens and their base lotion to different sites. Nickel-containing patches were then applied to both UV-treated sites and adjacent, unirradiated control sites. Erythema caused by nickel CHS at each site was quantitated 72 h later with a reflectance erythema meter. In comparison of the nickel reactions of irradiated and unirradiated skin, there was 35% mean immunosuppression in unprotected UV-treated skin. Significant immunosuppression also occurred at sites irradiated through the narrow-spectrum cinnamate-only sunscreen but was prevented by the two broad-spectrum sunscreens. To determine whether UV-induced suppression of the nickel response is specific for cell-mediated immunity or reflects suppression of nonspecific inflammation, a further 16 subjects were patch-tested with a skin irritant, sodium lauryl sulfate (SLS), following a sunscreen and irradiation protocol identical to that of the nickel volunteers. UV had no significant effect on SLS responses. We conclude that nickel patch testing is a valid means of assessing UV-induced immunosuppression in humans and that even with suberythemal UV, immune protection was provided only by sunscreens filtering both UVA and UVB.

Histamine involvement in UVB- and cis-urocanic acid-induced systemic suppression of contact hypersensitivity responses

Studies in experimental models have implicated histamine and prostanoids in ultra-violet B (UVB)- and cis-urocanic acid (UCA)-induced systemic immunosuppression. This study examined the hypothesis that UVB irradiation and cis-UCA suppressed contact hypersensitivity responses to hapten by induction of histamine, which in turn evoked a prostanoid-dependent component of immunosuppression. BALB/c mice were administered with a cis-UCA monoclonal antibody, a combination of histamine types 1 and 2 receptor antagonists, or indomethacin. Mice were sensitized to 2,4,6-trinitrochlorobenzene (TNCB) on their ventral surface 5 days after UVB irradiation, or cis-UCA or histamine administration. Ears were challenged with TNCB 5 days later. Cis-UCA antibody inhibited the suppressive effects of UVB by approximately 60% and confirmed that suppression of contact hypersensitivity responses by UVB was due, at least in part, to mechanisms involving cis-UCA. Histamine suppressed contact hypersensitivity responses and the effects of cis-UCA and histamine were not cumulative, suggesting that cis-UCA and histamine signal largely through the same pathway. The immunosuppressive effects of histamine were not affected by the cis-UCA antibody, consistent with the model that histamine acts downstream of cis-UCA. Administration of histamine receptor antagonists and indomethacin each approximately halved the UVB- and cis-UCA-induced systemic suppression of contact hypersensitivity responses. The effects of the reagents that inhibited the action of histamine and prevented prostanoid production were not cumulative, and suggested involvement in the same pathway. These results support the involvement of cis-UCA, histamine and prostanoids, in a sequence, in UVB-induced systemic suppression of contact hypersensitivity responses.