Epidermal cytokines in allergic contact dermatitis

The Skin and Inflamm-Aging

With its unique anatomical location facing both the external and internal environment, the skin has crucial functions, including shielding the body from damage caused by ultraviolet radiation and chemicals, preventing water loss, acting as a primary barrier against pathogens, participating in metabolic processes like vitamin D production and temperature control and relaying information to the body through sensory and proprioceptor nerves. Like all organ systems, skin is known to undergo multiple changes with aging. A better understanding of the mechanisms that mediate aging-related skin dysfunction may allow the creation of targeted therapeutics that have beneficial effects not only on aged skin but also on other organs and tissues that experience a loss of or decline in function with aging. The skin is the largest organ of the body and can contribute to serum inflammatory mediator levels. One alteration known to occur with age is an impairment of skin barrier function; since disruption of the barrier is known to induce inflammation, skin may be a major contributor to the sustained, sub-clinical systemic inflammation associated with aging. Such "inflamm-aging" may underlie many of the deleterious changes observed in aged individuals. This review explores the role of age-related skin changes, skin inflammation and inflamm-aging.

Sarsasapogenin and fluticasone combination improves DNFB induced atopic dermatitis lesions in BALB/c mice

OBJECTIVE

Atopic dermatitis (AD) is a pruritic, chronic, relapsing inflammatory skin disease. The research aims to study the effects of Sarsasapogenin and its combination with Fluticasone in 2, 4-Dinitrofluorobenzene (DNFB) induced atopic dermatitis in BALB/c mice.

MATERIAL AND METHODS

Thirty male Balb/c mice were divided into 5 groups: (i) Normal control (NC), (ii) Disease control (DNFB), (iii) Sarsasapogenin (SG) (50 µg/mice), (iv) Fluticasone (FC) (50 µg/mice), (v) Sarsasapogenin + Fluticasone (SG + FC) combination (25 µg/mice). Dermatitis was induced by repeated application of DNFB in Balb/c mice. On topical application of SG, FC, and SG + FC combination on the ear and skin lesions, body weight, ear weight, ear thickness, erythema score, spleen weight, cytokines, immunoglobulin E (IgE) levels, nitric oxide (NO) level, hematological parameters, and oxidative stress markers were evaluated. Histological analysis of the ear tissue was also done.

RESULTS

The results stated that SG and SG + FC treatment to mice considerably decrease the ear weight, ear thickness, spleen weight, serum IgE, cytokines, NO levels, and restoration of antioxidant stress markers with elevation in the hematological parameters. The observations were further confirmed by histopathological analysis of ear tissue.

CONCLUSION

These data specify that SG has been demonstrated as a probable therapy for the treatment of allergic skin diseases in combination with FC by decreasing its dose from 50 to 25 µg/mice to avoid the chronic side effects of FC. Hence, it can be concluded that SG and SG + FC combination significantly improved the AD-like symptoms in the DNFB sensitized mice through mitigating the production of proinflammatory mediators and restoration of oxidative stress markers.

Ameliorative Effect Of Zinc Oxide Nanoparticles Against Dermal Toxicity Induced By Lead Oxide In Rats

Background

Recently, several studies demonstrate the possible role of zinc oxide (ZnO) in the protection of several skin diseases, but less is known about the role of ZnO nanoparticles in the inflammatory skin disease. So, this study was designed to confirm the pivotal role of the nano zinc oxide cream in the alleviation of lead oxide (PbO) induced-allergic dermatitis in rats.

Materials and methods

Two concentrations (1% and 6%) of ZnONPs creams were prepared and characterized prior to being used in the study. A total number of 30 male Wistar rats were randomly divided into six groups. Group 1 (negative control), groups 2&3 (either 1% or 6% ZnONPs control groups), group 4 (PbO), groups 5&6 (co-treatment of each ZnONPs concentration+PbO). All rats in different groups were observed daily to determine the severity of dermal gross lesions. Histopathological studies, mRNA analysis, and oxidative stress evaluations were performed on the affected skin tissue. Immunohistochemical studies were performed to evaluate the expression of cluster of differentiation CD4, CD8 and intercellular adhesion molecules ICAM-1 in different groups.

Results

PbO caused extensive skin oxidative damage manifested by a significant increase in MDA level with a decrease in GSH content and CAT activity. The results of histopathological and immunohistochemical examinations revealed that topical application of PbO for 14 days led to severe allergic dermatitis with remarkable elevations in the number of CD4+ T-helper, CD8+ T-cytotoxic lymphocytes, and ICAM-1 expression. On the other hand, noticeable improvements were recorded in all the previous toxicopathological parameters among the groups treated by either 1% or 6% ZnO-NPs cream. However, the best results were observed in the group treated with 1% ZnO-NPs cream.

Conclusion

Our findings suggest that 1% of ZnO-NPs cream is safe when applied topically on the inflamed skin. Moreover, it had anti-inflammatory and antioxidant effects so that, it is recommended to use the 1% ZnO-NPs cream to avert the dermal toxicity-induced by PbO.

Hexavalent chromium induced ROS formation, Akt, NF-kappaB, and MAPK activation, and TNF-alpha and IL-1alpha production in keratinocytes

In certain cell types, it has been found that, hexavalent chromium could increase ROS formation, activate cell signaling and stimulate the release of cytokines. But, in keratinocytes, these effects have not yet fully been demonstrated. Our aim is to observe the above effects of hexavalent chromium on keratinocytes. By utilizing HaCaT cells and the skin of albino guinea pigs, we showed that hexavalent chromium could increase ROS formation, activate the Akt, NF-kB, and MAPK pathways as well as increase the production of cytokines, including TNF-alpha and IL-1alpha. The release of these cytokines from keratinocytes is considered to be a key participant in the pathogenesis of contact hypersensitivity. Among cement workers, chromium hypersensitivity is an important occupational skin disease issue. Therefore, the observations of our study help us better understand the role of hexavalent chromium on the development of chromium hypersensitivity, which might provide clues for clinicians in the development of chemopreventative agents for the prevention of chromium hypersensitivity among cement workers.

Effects and mechanisms of aloperine on 2, 4-dinitrofluorobenzene-induced allergic contact dermatitis in BALB/c mice

Allergic contact dermatitis is a prototypic T-cell-mediated cutaneous inflammatory response. Multiple cell types, inflammatory mediators and cytokines are involved in the regulation of immunologic and inflammatory processes in allergic contact dermatitis. Aloperine is an isolated alkaloid found in the plant of Sophora alopecuroides L. It has been clinically proved effective in China for a long time for skin inflammatory diseases such as allergic contact dermatitis. However, the mechanism of aloperine on allergic contact dermatitis is largely unknown. Therefore, the aim of this study was to investigate the effect of aloperine on 2, 4-dinitrofluorobenzene (DNFB)-induced allergic contact dermatitis in BALB/c mice and the possible underlying mechanisms. The results showed that topical application of DNFB on the ear provoked typical allergic contact dermatitis with ear swelling and ear erythema in BALB/c mice. Treatments with 1% aloperine suppressed DNFB-induced increase in ear thickness and ear erythema. Moreover, 1% aloperine treatment significantly decreased the up-regulated mRNA and protein levels of tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta) and interleukin-6 (IL-6) induced by DNFB in ear biopsy homogenates. Our findings suggest that aloperine greatly improves the DNFB-induced allergic contact dermatitis in mice. The therapeutic mechanism might be related to the reduction of TNF-alpha, IL-1beta and IL-6 production induced by DNFB.

Topical nanocrystalline silver cream suppresses inflammatory cytokines and induces apoptosis of inflammatory cells in a murine model of allergic contact dermatitis

BACKGROUND

Nanocrystalline silver has both antimicrobial and anti-inflammatory properties. However, the exact mechanisms underlying these activities are not known.

OBJECTIVES

The objectives of this study were to assess the anti-inflammatory effects of nanocrystalline silver using a murine model of allergic contact dermatitis, compare the effects with those of tacrolimus and a high potency steroid, and to relate the effects to modulation of pro-inflammatory cytokines and apoptosis of inflammatory cells.

METHODS

Dermatitis was induced on the ears of BALB/c mice using dinitrofluorobenzene. Topical treatment, including vehicles, 1% nanocrystalline silver cream, tacrolimus ointment and a high potency steroid, was applied once a day for 4 days. Ear swelling was measured and the erythema was evaluated daily. After 4 days of treatment the mice were killed and samples from the ears were collected for histological and immunohistochemical examination, terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-biotin nick end labelling (TUNEL) staining and extraction of total RNA for reverse transcriptase polymerase chain reaction (RT-PCR).

RESULTS

Significant reductions of ear swelling, erythema and histopathological inflammation in mice ears were observed after 4 days of treatment with 1% nanocrystalline silver cream, tacrolimus ointment or a high potency steroid with no significant difference among them. Both RT-PCR and immunohistochemical staining of sections from ear biopsies demonstrated that nanocrystalline silver, tacrolimus and steroid significantly suppressed the expression of tumour necrosis factor (TNF)-alpha and interleukin (IL)-12. TUNEL staining demonstrated a significant increase in the numbers of apoptotic cells in material from the group treated with nanocrystalline silver when compared with that from groups treated with vehicle, tacrolimus or steroid.

CONCLUSIONS

This study demonstrates that nanocrystalline silver inhibits allergic contact dermatitis in mice, similar to steroid and tacrolimus. Nanocrystalline silver suppresses the expression of TNF-alpha and IL-12 and induces apoptosis of inflammatory cells; mechanisms by which nanocrystalline silver may exert its anti-inflammatory effects.

Immunomodulatory effects of low-intensity near-infrared laser irradiation on contact hypersensitivity reaction

BACKGROUND/PURPOSE

Contact hypersensitivity (CHS) reaction is a useful model for studying the skin immune system and inflammatory reactions in the skin. In this study, an experimental model of CHS reaction was employed to assess immunomodulatory effects of near-infrared (near-IR) low-intensity laser (LIL) irradiation, which is used as adjuvant therapy in dermatology, physical medicine, rheumatology, etc., because of its declared anti-inflammatory, biostimulative and analgesic effects.

METHODS

The effects of near-IR LIL irradiation (lambda=904 nm, irradiance 60 mW/cm2, fluence 3.6 J/cm2) on CHS reaction to 1-chloro-2,4-dinitrochlorobenzene (DNCB) in Albino Oxford rats were examined by irradiating experimental groups of animals before the induction phase of CHS reaction, while nonirradiated animals and animals that received vehicle instead of hapten served as controls. Ear-swelling assay, histopathological examination of H&E preparations of ear skin, computer-assisted image analysis of dermal infiltrate, ear skin organ culture with the determination of cutaneous production of tumour necrosis factor-alpha (by ELISA assay) and nitric oxide (by Griess' assay) were used for measuring the effects of LIL in the elicitation phase of CHS reaction. Cellularity, dendritic cell content, flow cytometry and proliferation assays (spontaneous and in the presence of IL-2 and concanavalin A) of the draining lymph node cells (DLNC) were performed for the assessment of LIL irradiation effects in the induction phase.

RESULTS

In the irradiated group of animals, ear swelling was significantly diminished compared to control animals (101+/-11.5% vs. 58+/-11.6%, P<0.01). This was accompanied by a highly significant decrease in the density of dermal infiltrate (22+/-0.81 vs. 14.2+/-1.75 cells per unit area, P<0.01) and a significant decrease in nitrite levels in the medium conditioned by organ-cultured ear skin (17.63+/-1.91 vs. 3.16+/-1.69 microM NaNO2; P<0.01), while TNF-alpha concentration was not changed. Cellularity and dendritic cell content in DLNC population, as well as the expression of TCR-alpha, CD4, CD8 and CD25, were not changed between irradiated and nonirradiated animals. Proliferation rates of DLNC cultured for 72 h were significantly lower in irradiated animals (17.3+/-4.1 vs. 13.9+/-0.9 x 103 c.p.m.; P<0.01). In cultures of DLNC with added rIL-2 or 0.5 microg/ml of concanavalin A, proliferation rates were also significantly decreased in irradiated animals (34.7+/-3.5 vs. 31.2+/-2. c.p.m. in IL-2-supplemented culture, P<0.01; 70.9+/-6.4 vs. 58.3+/-9.1 x 103 c.p.m. in concanavalin A-supplemented culture, P<0.01). However, this effect was overcome in the presence of the higher concentration of concanavalin A (2.5 microg/ml) (nonirradiated 38.7+/-3.1, irradiated 123.1+/-7.3 x 103 c.p.m., P<0.01).

CONCLUSION

LIL irradiation showed a systemic immunomodulatory effect on CHS reaction to DNCB in rats. Decreased ear swelling observed in the elicitation phase was associated with diminished proliferative responses of the DLNC in the induction phase of CHS reaction. Further experimental work is needed to examine the possible mechanisms of these effects.

Differential role of SLP-76 domains in T cell development and function

The adapter SLP-76 is essential for thymocyte development. SLP-76(-/-) mice were reconstituted with SLP-76 deletion mutant transgenes to examine the role of SLP-76 domains in T cell development and function. The N-terminal domain deletion mutant completely failed to restore thymocyte development. Mice reconstituted with Gads-binding site and SH2 domain deletion mutants had decreased thymic cellularity, impaired transition from double to single positive thymocytes, and decreased numbers of mature T cells in the spleen. Calcium mobilization and extracellular signal-regulated protein kinase activation were decreased in the Gads-binding site mutant but almost normal in the SH2 domain mutant. T cells from both mutants failed to proliferate following T cell antigen receptor ligation. Nevertheless, both mutants mounted partial cutaneous hypersensitivity responses and normal T cell dependent IgG1 antibody responses. These results indicate differential roles for SLP-76 domains in T cell development, proliferation and effector functions.

Positive responses to imipramine in the popliteal lymph node assay are due to primary irritation

The popliteal lymph node (PLN) assay has long been proposed as a tool to detect immunotoxicants with the potential to induce systemic autoimmunity. A major problem hampering the further validation of this assay is the need to rule out irritants that cause false-positive PLN responses. The anti-depressant, imipramine, has not been reported to induce systemic autoimmune reactions in treated patients, but has been repeatedly found positive in the PLN assay, suggesting that this is a false-positive response. To test this hypothesis, the effects of imipramine were compared to those of 50% ethanol in C57B1/6 mice. Footpad edema was evidenced in the few days after injection of both ethanol and imipramine. T-cell depletion using monoclonal antibodies against either CD4+ or CD8+ T-lymphocytes prior to the PLN assay did not influence the responses to either ethanol or imipramine. Cytokine (TNFalpha, IL-1alpha, IL-1beta, IL-2R, IL-6, IL-12 and IFN-gamma) fingerprinting of the PLNs after injection of ethanol and imipramine evidenced the same pattern of responses. These results indicate a closely similar pattern of responses following the footpad injection of either imipramine or ethanol. The conclusion can be drawn that imipramine induces positive responses in the PLN assay via primary (nonspecific) irritation.

Chemical activation of innate and specific immunity in contact dermatitis

Recent reports have suggested that chemical-induced allergic contact dermatitis may not be a traditional type IV hypersensitivity, in part due to the dual irritant and antigenic properties of sensitizing chemicals. In order to investigate the contribution of these properties to the molecular and cellular mechanism underlying allergic contact dermatitis, we evaluated oxazolone-induced changes in cell populations and cytokine production in the dermis of transgenic mice with impaired innate immunity (the FcgammaR subunit knockout mouse), and absent specific immunity (the athymic mouse), and the appropriate B6,129F2 and C57BL/6 control mice. Oxazolone and croton oil were applied in a single sensitizing dose, or in sensitizing and challenge doses, and the dermal response was evaluated by immunohistochemistry. In the wild type mice, with or without sensitization to oxazolone or croton oil, we observed mixed Th1/Th2 cytokine production and both CD4+ and CD8+ T lymphocytes; however, the neutrophil was the predominant cell in the dermis, even 72 h after final chemical application. Athymic mice displayed a similar neutrophil response with moderate Th1/Th2 cytokine production, and FcgammaR subunit knockout mice exhibited very mild dermatitis when treated with either oxazolone or croton oil. These results provide support for the hypothesis that allergic contact dermatitis is not a classic delayed type hypersensitivity, demonstrate the importance of the interaction between the irritant and antigenic properties of sensitizing chemicals in the development of allergic contact dermatitis, and suggest that the irritant effect of chemicals may be mediated through the cutaneous innate immune system.

Imiquimod, a topical immune response modifier, induces migration of Langerhans cells

Langerhans cells are bone marrow derived dendritic cells that represent the major antigen-presenting cells in the skin. Langerhans cells take up and process antigen within the epidermis and present processed antigen to T lymphocyte in the regional lymph nodes and thus form an integral part of the cutaneous immune response. The cutaneous immune response can be modified by a number of pharmacologic agents, including corticosteroids, cyclosporine, and retinoids as well as physical agents, such as ultraviolet light. For the most part these agents act by suppressing immune function. A topical immune response modifier, imiquimod has been shown to enhance the cutaneous immune response. Imiquimod has anti-viral and anti-tumor effects in animal models and has been approved for the topical treatment of external genital and perianal warts in humans. The biologic activity of imiquimod in part is due to its effect as a cytokine inducer. Preliminary data suggested that imiquimod could have an effect on Langerhans cells. In order to clarify this effect on Langerhans cells, we examined Langerhans cell morphology and migration in imiquimod-treated skin. The density of Ia + cells decreased 2 d after treatment, falling to approximately 43% by day 10. The Ia positive in cells remaining in the skin appeared larger and more dendritic suggesting an activated state. ATPase staining of epidermal sheet confirmed the decreased number of Langerhans cells. To clarify status of Langerhans cells, the activation of B7 was examined. Activation of B7-1 or B7-2 was not detected. Imiquimod, however, did enhance Langerhans cell migration from skin to draining lymph nodes. This enhanced Langerhans cell migration was also associated with an enhanced allergic contact hypersensitivity. These results suggest that the mechanism of modulation of immune response by imiquimod is in part due to effects on Langerhans cells.

A macrolactam inhibitor of T helper type 1 and T helper type 2 cytokine biosynthesis for topical treatment of inflammatory skin diseases

T lymphocytes play a critical part in inflammatory skin diseases but are targeted by available therapies that have only partial efficacy, significant side-effects, or both. Because psoriasis, atopic dermatitis, and allergic contact hypersensitivity are associated with T helper type 1 (Th1), T helper type 2 (Th2), or mixed Th1-Th2 cell subsets and cytokine types, respectively, there is a need for a better broad-based inhibitor. The macrolactam ascomycin analog, ABT-281, was found to inhibit potently T cell function across species and to inhibit expression of multiple cytokines in human peripheral blood leukocytes which have been found in human skin disease cells and tissues. These included immunoregulatory Th1 (interleukin-2 and interferon-gamma) and Th2 (interleukin-4 and interleukin-5) cytokines. ABT-281 was shown to have potent topical activity (ED50 = 0.6% in acetone/olive oil) in a stringent swine model of allergic contact hypersensitivity, but its potency was markedly reduced compared with ascomycin when administered systemically due to more rapid clearance. Topical application of 3% ABT-281 in acetone/olive oil over 25% of the body surface in swine resulted in undetectable blood levels. Compared with a wide potency range of topical corticosteroids in clinical formulations, 0.3% and 1% ABT-281 ointments profoundly inhibited dinitrochlorobenzene-induced contact hypersensitivity in the pig by 78% and 90%, respectively, whereas super-potent steroids such as clobetasol propionate only inhibited in the 50% range and mild to moderate potency steroids such as fluocinolone acetonide were inactive. The potent topical activity of ABT-281 in swine, its superior efficacy, its rapid systemic clearance following uptake into the bloodstream, and its ability to inhibit cytokine biosynthesis of both Th1 and Th2 cell subsets, suggests that it will have a broad therapeutic value in inflammatory skin diseases, including psoriasis, atopic dermatitis, and allergic contact dermatitis.

Epithelium-fibroblast co-culture for assessing mucosal irritancy of metals used in dentistry

No valid animal or in vitro model exists to assess the potential mucosal irritancy of dental materials. However, recently, a commercially available model system based on a recombined co-culture of human fibroblasts and human epithelial cells has been introduced for evaluating the time-dependent irritancy of cosmetic products. Cell viability and prostaglandin E2 (PGE2) release from the cells were used as markers for the irritative potential of test materials. The objective of the present study was to evaluate the suitability of this model for monitoring the irritative potential of metals and cast alloys used in dentistry. The human fibroblast-keratinocyte co-cultures were exposed to test specimens fabricated from copper, zinc, palladium, nickel, tin, cobalt, indium, a high noble cast alloy, and from a dental ceramic. Cell survival rates decreased after exposure to copper (14-25%), cobalt (60%), zinc (63%), indium (85%), nickel (87%), and the non-oxidized and oxidized high noble cast alloy (87%/90%) compared to untreated control cultures. Dental ceramic, palladium and tin did not influence cell viability. In parallel, the PGE2 release was continuously monitored up to 24 h using a competitive displacement enzyme immunoassay. PGE2 release increased most highly in the cultures exposed to copper (6-25 fold), cobalt (7 fold), indium (4 fold), and zinc (2 fold) compared to untreated control cultures. The PGE2 determination proved to be a non-destructive method for continuous monitoring of cell reactions in the same culture. The model used seems promising for evaluating the time-dependent mucosal irritancy of dental cast alloys.

Leukaemia inhibitory factor: induction in the early phase of allergic contact dermatitis

It has been suggested that leukaemia inhibitory factor (LIF), may be involved in the pathogenesis of cutaneous inflammation. In 5 patients with previously proven contact allergy to nickel, LIF mRNA and protein expression were assessed by reverse transcription-polymerase chain reaction and immunohistochemistry in 5% nickel sulfate patch test biopsies 24 h after application of the patch. Control specimens were obtained from non-tested and vehicle-tested skin from the same individuals. LIF mRNA expression was significantly increased in nickel-tested skin compared with both vehicle-tested (p = 0.045) and non-tested skin (p = 0.041). All biopsies showed similar patterns of LIF immunoreactivity, with no significant differences between nickel-tested, vehicle-tested and non-tested skin. Immunostaining was cytoplasmic and was present in the epidermis and hair follicles. No dermal staining was observed. This study suggests that LIF may play a role in the early phase of allergic contact dermatitis.

The role of CD4 molecules in the induction phase of contact hypersensitivity cytokine profiles in the skin and lymph nodes

We have previously demonstrated that CD4 gene-targeted mutant mice (CD4- mice) demonstrate hyporesposiveness in contact hypersensitivity (CHS) suggesting that CD4 molecules are required for optimal induction of CHS. In the present study, we wished to examine the mechanisms of this hyporesponsiveness, in particular, we examined whether cytokines were altered in the skin and lymph nodes of CD4- mice following exposure to the contact allergen dinitrofluorobenzene (DNFB). Cytokine mRNA in the ear skin and draining lymph nodes (DLN) were examined by reverse transcription-polymerase chain reaction (RT-PCR) at various times after sensitization. Skin cytokine patterns revealed that in normal mice, interleukin (IL)-2, interferon (IFN)-gamma and tumour necrosis factor (TNF)-alpha mRNA levels increased at 12 hr sensitization, whereas these cytokines were below the level of detection in CD4- mice. In the DLN of normal mice following the hapten application, sequential upregulation of cytokine mRNA including IL-1 alpha, IL-1 beta, IL-2, IL-4, IL-10, IFN-gamma and TNF-alpha was found. No change was seen for IL-1 alpha, IL-1 beta, IL-10 and TNF-alpha and IL-2, IL-4 and IFN-gamma mRNA levels were below the level of detection in DLN from CD4- mice following the hapten application. However, IL-1 beta, IL-2 and TNF-alpha mRNA levels of lymph node cells from CD4- mice could be upregulated by phorbol myristate acetate in vitro. Flow cytometry study has revealed that the number of Langerhans' cells (LC) in DLN of CD4- mice was similar to that of normal mice, thus, inferring that the alterations of cytokine milieu in the ear skin did not have a significant effect on LC migration to DLN. These results suggest that CD4 molecules are crucial for the induction of certain cytokines in the skin and in inducing sequential cytokine signals in DLN required for optimal development of CHS, but that these changes in cytokines do not effect LC migration.

Hyporesponsiveness in contact hypersensitivity and irritant contact dermatitis in CD4 gene targeted mouse

To determine the role of CD4 molecules in the generation and regulation of contact hypersensitivity (CHS), we treated mice lacking the CD4 gene as a result of targeted disruption with dinitrofluorobenzene to induce CHS. The mutant mice lacking CD4 (CD4(-) mice) showed marked hyporesponsiveness in CHS compared with normal syngeneic C57BL/6 mice (38.3 +/-9.0% of normal at 24 h after the challenge assessed by net ear swelling; p < 0.025). CD4(-) mice had a larger CD4-8- double negative T-cell receptor alpha beta+ cell population in the lymph nodes than did normal mice, and the increase of this cell population was observed in CD4(-) mice after sensitization. Draining lymph node cells from sensitized normal mice restored the responsiveness in CD4(-) mice, but those from sensitized CD4(-) mice were less effective in restoring the CHS response in normal mice. Langerhans cell numbers were normal, and function, as assessed by the ability to present soluble hapten, was not impaired in CD4(-) mice. Skin cytokine profiles demonstrated an increase in interferon-gamma, interleukin-2, and interleukin-4 mRNA levels after challenge in normal mice, whereas this response was blunted in CD4(-) mice. CD4(-) mice also showed hyporesponsiveness in inflammatory reaction to irritant chemicals. These results suggest that the CD4 molecule is required for optimal induction of CHS as well as irritant contact dermatitis and may influence the development of CHS by modulating the cytokine profiles in the skin.