Application Of Dinitrochlorobenzene Research Articles

Moisturizing Nanoemulgel of Turmeric (Curcuma longa) Rhizome Extract Ameliorates Atopic Dermatitis-like Skin Lesions in Mice Model through Thymic Stromal Lymphopoietin, Interleukin-13, and Interleukin-17

ABSTRACT Introduction: Various moisturizers have been developed for mild and moderate atopic dermatitis (AD). Turmeric (Curcuma longa), containing a potent anti-inflammatory substance, is one of the promising ingredient for moisturizers. By formulating turmeric into nanoemulgel preparation, cutaneous absorption is enhanced. This study aims to determine the effect of 1% turmeric rhizome extract moisturizing nanoemulgel on thymic stromal lymphopoietin (TSLP), interleukin (IL)-13, IL-17 levels, histopathological feature, transepidermal water loss (TEWL) value, and dermatitis score in an AD-like mouse model induced by dinitrochlorobenzene (DNCB). Methods: This study used 35 female BALB/C mice aged 6–8 weeks, weighing 20–30 g. Mice were divided into the treatment group (DNCB and 1% turmeric rhizome extract moisturizing nanoemulgel) and the control group (DNCB and vehicle gel). The DNCB application was carried out twice a week, from day 14 to day 29. On day 30, skin tissue samples were taken to examine TSLP, IL-13, IL-17 levels, and histopathological examination. Results: The treatment group showed lower TSLP, IL-13, and skin tissue IL-17 levels than the control group (P < 0.05). In addition, applying 1% turmeric rhizome extract, moisturizing nanoemulgel improved the treatment group’s dermatitis score and histopathological features compared to the control group (P < 0.05). The 1% turmeric extract moisturizing nanoemulgel decreased the TEWL but was statistically insignificant compared to the control group (P > 0.05). Conclusions: Applying 1% turmeric rhizome extract moisturizing nanoemulgel ameliorates AD-like skin lesions by decreasing TSLP, IL-13, and IL-17 levels in the DNCB-induced BALB/c mouse model.

Effect of 6'-acetylpaeoniflorin on dinitrochlorobenzene-induced allergic contact dermatitis in BALB/c mice.

Allergic contact dermatitis (ACD) is a classical experimental model of allergic inflammatory skin disease, which is a delayed-type hypersensitivity reaction that is mediated by hapten-specific T lymphocytes. The goal of this study was to investigate the pharmacokinetic profiles of 6'-acetylpaeoniflorin (6-AP) and the effect of 6-AP on the ACD model. 6-AP was synthesized from paeoniflorin (Pae) via acetylation, and the structure was confirmed. There were statistically significant differences in the pharmacokinetic parameters including t 1/2α , t 1/2β , AUC, MRT and C max among the animals that were orally administered Pae and 6-AP. An ACD model was induced using immunization with dinitrochlorobenzene (DNCB) in BALB/c mice. The mice were orally administered 6-AP (35, 70 and 140mg/kg/d), Pae (70mg/kg/d) and prednisone (Pre, 5mg/kg/d) from day 1 to day 7 after immunization. The results indicated that the topical application of DNCB to the skin provoked obvious inflammatory responses. 6-AP significantly inhibited ear swelling and decreased inflammatory cell infiltration and epidermal keratinization. Additionally, 6-AP observably alleviated the hyperplasia of red pulp and germinal center appearance, decreased the spleen index and inhibited splenocyte proliferation in the ACD model compared to that of Pae. Furthermore, the study indicated that 6-AP could increase the IL-10 level, while simultaneously reducing the IL-17 level in splenocytes. In summary, these results suggest that 6-AP has a significantly higher anti-inflammatory effect than Pae and that 6-AP might be a candidate for the treatment of allergic skin diseases.

Paeoniflorin inhibits inflammatory responses in mice with allergic contact dermatitis by regulating the balance between inflammatory and anti-inflammatory cytokines

Paeoniflorin (Pae) was previously reported to inhibit inflammation in the skin of mice with allergic contact dermatitis (ACD); however, the mechanism remains unclear. The primary purpose of this study was to investigate the effect of Pae on the regulation of cytokine production in a murine model of ACD. ACD was induced in the mice by repeated application of dinitrochlorobenzene (DNCB) to their skin. Cutaneous inflammation was evaluated by measuring ear swelling and by histological examination. The cytokine levels were measured by enzyme-linked immunosorbent assays. The results showed that topical application of DNCB caused obvious swelling and inflammatory cell infiltration. Treatment with Pae (70 or 140mg/kg/d) significantly inhibited the cutaneous inflammation and decreased thymocyte proliferation in the mice with ACD. Additional data indicated that Pae increased interleukin-4 (IL-4) and IL-10 production but reduced IL-2 and IL-17 levels in the serum as well as in thymocyte and splenocyte culture supernatants. As expected, IL-2 and IL-17 levels in the serum displayed a significant positive correlation with the severity of skin inflammation. In contrast, IL-4 and IL-10 levels were negatively correlated with the inflammation. The anti-inflammatory action of Pae in the murine model of ACD may be related to its regulation of an imbalanced cytokine production.

Pimecrolimus kremin (%1) atopik dermatit tedavisindeki etkinliği

SummaryBackgroundIn recent years, pimecrolimus 1% cream has been demonstrated to reduce symptoms of atopic dermatitis in patients when applied topically.Material/MethodsIn our study we compared the therapeutic effects of local 1% pimecrolimus to 1% hydrocortisone, and to a control group in a mouse model with atopic dermatitis in the external ear canals. Atopic dermatitis was created by application of Dinitrochlorobenzene in the external ear canals of mice. The development of atopic dermatitis was detected by clinical observation score and determination of total serum IgE levels. Pimecrolimus and hydrocortisone cream were topically applied to the external ear canal skin once a day for 14 days.ResultsThere was no significant difference between the hydrocortisone and the pimecrolimus therapy groups, while there was a statistically significant difference between these 2 groups and the control group (p<0.05) Assessment of the clinical observation scoring carried out on the 14th day of therapy revealed that there was no difference between the hydrocortisone and pimecrolimus groups. Biopsies were taken on the 14th day following treatment. Tissue samples were histologically evaluated; contact dermatitis was observed microscopically in the control group, but in the therapy groups only minimal evidence of contact dermatitis was found.ConclusionsThe results of our study reveal that the therapeutic efficacy of 1% pimecrolimus was equivalent to 1% hydrocortisone treatment in the artificially developed atopic dermatitis model in external ear canals of mice. These results clearly demonstrate that 1% pimecrolimus cream can be an effective alternative therapeutic agent in cases where steroid treatment proves to be insufficient or in cases where treatment must be discontinued due to its adverse effects.

Systemic immunomodulatory effects of topical dinitrochlorobenzene (DNCB) in rats. Activity of peripheral blood polymorphonuclear cells

Topical application of dinitrochlorobenzene (DNCB) is employed in the immunotherapy of skin diseases. Activation of T-cell mediated immune responses (Th1/type1) is the supposed mechanism of the clinical effect of DNCB, but there are no data concerning innate/inflammatory mechanisms. In this study, the effect of repeated topical DNCB application on peripheral blood polymorphonuclear (PMN) leukocytes has been examined in two rat strains which differ in the propensity to mount Th1/type1 or Th2/type2 responses. The dynamics of changes in PMN numbers and effector activities (respiratory burst, nitric oxide production and myeloperoxidase content), as well as in adhesion and TNF-α production following the rat skin sensitization with low (0.4%) and high (4%) DNCB doses were measured. Both priming and activation of PMNs were observed following skin sensitization with DNCB, with dose-dependent as well as time-dependent differences in some PMN activities. Obtained data might be relevant for understanding the immune mechanisms of topical DNCB therapy.

Percutaneous toxicity of dinitrochlorobenzene (DNCB) in rats

Contact hypersensitivity reaction (CHS) is a T-cell-mediated skin inflammatory reaction to cutaneous exposure to small sensitizing chemicals, haptens. While the significance of local inflammatory skin response to the hapten application in CHS induction and expression is known, there is paucity of data concerning systemic inflammation in CHS. In this study, changes in cellular (peripheral blood granulocytes) and humoral (plasma tumor necrosis factor (TNF)-α levels) components of inflammation during sensitization of rats with two consecutive applications of dinitrochlorobenzene (DNCB) were examined. The impact of sensitization on these parameters was determined by employing low (0.4%) and high (4%) hapten doses and by examining the dynamics (i.e. one and three days following the last application of DNCB) of these changes. Dose-dependent increase in relative numbers and priming (for respiratory burst and adhesion) effect of skin sensitization with DNCB on peripheral blood neutrophils in rats were noted. No changes in circulating TNF-α levels were observed following the sensitization. The increase in lung myeloperoxidase content and histologically evident presence of neutrophils was observed in lungs of the sensitized rats. The changes in granulocyte priming for adhesion might have accounted for the observed increase in lung neutrophil content in the sensitized rats.

Contact allergic response to dinitrochlorobenzene (DNCB) in rats: Insight from sensitization phase

Contact hypersensitivity (CHS) is a T-cell-mediated skin inflammatory reaction to cutaneous exposure to small sensitizing chemicals, haptens. Majority of CHS studies were conducted in mice and there is paucity of data in other experimental animals. In the present study, characteristics of contact hypersensitivity reaction to dinitrochlorobenzene (DNCB) were determined in Th1-prone Dark Agouti (DA) rats by evaluating sensitization phase as a function of time-dependent changes in draining lymph nodes (DLN). Apart from basic indices of DLN activity (cellularity and proliferation), the production of cytokines relevant for CHS induction, interleukin-6 (IL-6), interferon-γ (IFN-γ), interleukin-17 (IL-17) and interleukin-4 (IL-4) was analyzed. Anti-inflammatory cytokine interleukin-10 (IL-10) production by DLN cells was determined as well. Highest production of IL-6, IFN-γ and IL-17 in sensitized animals was observed at day 3 after DNCB application, with a decrease at day 5. Increased messages for IFN-γ and IL-17 were noted at this time point. In contrast to inflammatory cytokines, anti-inflammatory cytokine interleukin-4 (IL-4) was undetectable during the entire sensitization phase. Differential pattern (IL-6 and IFN-γ) and level (IFN-γ and IL-17) of inflammatory cytokine production was noted in sensitized Th2-prone Albino Oxford (AO) rats. Similarly to DA rats, no changes in IL-4 were noted in AO rats. Strain-dependent differences in inflammatory cytokine production seem to be based on anti-inflammatory cytokine interleukin-10 (IL-10). Production of IFN-γ concomitantly with undetectable IL-4 in both strains classify rat CHS to DNCB as Th1/type 1 reaction. Detection of IL-17 in sensitized DLN cells points to the involvement of T IL-17 cells in rat contact hypersensitivity.

Age and gender effects on contact sensitization and photoimmune suppression in young and middle‐aged adults

The contact hypersensitivity (CHS) response has been used to assess ultraviolet radiation (UVR)-induced immunosuppression and to evaluate the photoimmune protection of different sunscreen preparations in vivo. Earlier reports of the effect of age and gender on CHS response have led to variations in inclusion criteria for participants in regards to age and gender in the study of sunscreen immune protection factor (IPF). This study is a retrospective analysis of data from 73 volunteers from prior CHS studies with the goal of determining the effect of age and gender in young and middle-aged adults on CHS response to dinitrochlorobenzene (DNCB) in unirradiated and UV-irradiated skin. In patients aged 18-63 years, the effect of age on CHS response as well as on UV suppression of CHS response was not statistically significant. In the unirradiated (n=45) and UV-irradiated (n=28) groups, the CHS response between men and women was similar when the timing of DNCB application avoided the period within 5 days before or after the first day of the menstrual cycle. Within a certain range, 18-63 years, age does not significantly affect the normal CHS response and the suppression of CHS response by UV. This study also demonstrated that as long as certain days of the menstrual cycle are avoided when sensitizing women of reproductive age, gender does not significantly affect CHS response. Thus, within these parameters, CHS can be appropriately evaluated in healthy individuals without much concern regarding independent effects of age and gender.

NCB-02 (standardized Curcumin preparation) protects dinitrochlorobenzene-induced colitis through down-regulation of NFκ-B and iNOS

To evaluate the efficacy and mechanism of action of NCB 02, a standardized Curcumin preparation, against 2, 4 dinitrochlorobenzene (DNCB) induced ulcerative colitis in rats. Ulcerative colitis was induced in male rats by sensitizing with topical application of DNCB in acetone for 14 d and intra-colonol challenge with DNCB on day 15. A separate group of animals with vehicle treatment in similar fashion served as control group. Colitis rats were divided into different groups and treated with NCB-02 at doses of 25, 50 and 100 mg/kg b.wt p.o. for 10 d. Sulfasalazine at a dose of 100 mg/kg b.wt for 10 d served as a reference group. On day 10 after respective assigned treatment, all the animals were euthanized and the length of the colon, weight of entire colon and distal 8 cm of the colon were recorded. The distal part of the colon was immediately observed under a stereomicroscope and the degree of damage was scored. Further distal 8 cm of the colon was subject to the determination of colonic myeloperoxidase (MPO), lipid peroxidation (LPO) and alkaline phosphatase (ALP) activities. A small piece of the sample from distal colon of each animal was fixed in 10% neutral buffered formalin and embedded in paraffin wax and sectioned for immunohistochemical examination of NFkappa-B and iNOS expression. NCB-02 showed a dose dependent protection against DNCB-induced alteration in colon length and weight. NCB-02 treatment also showed a dose dependent protection against the elevated levels of MPO, LPO and ALP, induced by DNCB. NCB-02 demonstrated a significant effect at a dose of 100 mg/kg b.wt., which was almost equipotent to 100 mg/kg b.wt. of sulfasalazine. Treatment with sulfasalazine and curcumin at a dose of 100 mg/kg b.wt. inhibited the DNCB-induced overexpression of NFkappa-B and iNOS in the colon. Curcumin treatment ameliorates colonic damage in DNCB induced colitic rats, an effect associated with an improvement in intestinal oxidative stress and downregulation of colonic NFkappa-B and iNOS expression.

TARC and RANTES, but not CTACK, are induced in two models of allergic contact dermatitis. Effects of cilomilast and diflorasone diacetate on T-cell-attracting chemokines

Skin-infiltrating T cells play a predominant role in allergic and inflammatory skin diseases such as atopic dermatitis and allergic contact dermatitis. These T cells are attracted by chemotactic factors, e.g. RANTES (regulation on activation, normal T cell expressed and secreted; CCL5), TARC (thymus and activation regulated chemokine; CCL17) and CTACK (cutaneous T-cell attracting chemokine; CCL27). To investigate which T-cell-attracting chemokines are involved in allergic contact dermatitis in mice. Allergic contact dermatitis was induced by application of dinitrochlorobenzene (DNCB) or toluene-2,4-diisocyanate (TDI), and chemokine concentrations were determined by enzyme-linked immunosorbent assay. The effects on chemokine concentrations of the highly selective phosphodiesterase 4 inhibitor cilomilast and the glucocorticoid diflorasone diacetate were studied in mouse ears. RANTES and TARC were elevated in both models of allergic contact dermatitis 24 h after challenge, whereas CTACK remained unchanged. The increase in RANTES was diminished in mouse ears pretreated with cilomilast or diflorasone diacetate. TARC was reduced by diflorasone diacetate in the DNCB model but was highly induced in the TDI model; in contrast, TARC was not influenced by cilomilast. TARC and RANTES, but not CTACK, are involved in these two models of allergic contact dermatitis.

Immunotoxicity of epicutaneously applied anticoagulant rodenticide warfarin: evaluation by contact hypersensitivity to DNCB in rats

The immunotoxicity of epicutaneously administered anticoagulant rodenticide warfarin (WF) was examined in this work by using experimental contact hypersensitivity (CHS) reaction to hapten dinitrochlorobenzene (DNCB). WF (0.05 and 0.5 mg/kg) administration 24 h before the induction of CHS does not change expression of CHS evaluated by ear swelling assay. Regional draining lymph node response during sensitization phase was characterized by decreased cellularity but increased spontaneous and IL-2 stimulated proliferation of draining lymph node cells (DLC). No changes in IL-2 production and in numbers of CD25 + cells were noted and even decreased proliferative index (ratio of IL-2 stimulated to unstimulated DLC proliferation) was detected. Increase in granulocyte activity (MTT reduction and adhesion to plastic) was noted following application of WF solely with further increase following subsequent application of DNCB, when granulocyte activation (NBT reduction) was noted also. Access of WF into general circulation might be responsible for observed changes, what was supported by ex vivo changes in DLC and granulocyte functions assessed before initiation of sensitization and by in vitro effect of exogenous WF as well. Differential effects of WF on lymphocytes and granulocytes noted in this study highlight the need for simultaneous testing of both cell type activity what might constitute a more integrated approach in immunotoxicity studies.

Chemoimmunotherapy for melanoma with dacarbazine and 2,4-dinitrochlorobenzene: results from a murine tumour model.

An empirically established chemoimmunotherapy that combines the epifocal application of the contact sensitizer dinitrochlorobenzene (DNCB) to cutaneous metastases with the systemic administration of dacarbazine (DTIC) yields high response rates and results in prolonged survival. However, despite the fact that this therapy has been in clinical use for several years, the mode of action still remains elusive. In order to overcome this limitation we established a murine model system. B16 melanoma cells were implanted subcutaneously in syngeneic C57BL/6 mice and treatment was started 7 days after. In a first set of experiments mice received intraperitoneal injections of DTIC followed by epifocal applications of DNCB 24 h later. Treatment significantly decreased tumour growth. In contrast, no significant effect was induced by DTIC or DNCB alone. Using this regimen, with varying doses of either DTIC or DNCB, we demonstrated that the therapeutic effect is dose dependent. Furthermore, the treatment of subcutaneous tumours with DTIC and DNCB influenced the course of visceral metastases: the growth of pulmonary metastases was significantly inhibited if subcutaneous tumours were treated as described. In conclusion, we have established a model system that seems to be appropriate for both the optimization of this therapeutic regimen and the characterization of effector mechanisms.

Assessment of Preferential T-Helper 1 or T-Helper 2 Induction by Low Molecular Weight Compounds Using the Local Lymph Node Assay in Conjunction with RT-PCR and ELISA for Interferon-γ and Interleukin-4

The local lymph node assay (LLNA) is a new and promising test in mice used to identify contact allergens by means of dermal exposure. Experimentally this assay, which comprises a sensitizing phase only, is also used to identify respiratory allergens. Another, experimentally used test in mice to identify allergens is also based on dermal exposure, but comprises both a sensitizing and effector phase. In this latter test, it has been shown that contact allergens preferentially induce a T-helper 1 (TH1) response, whereas respiratory allergens preferentially induce a T-helper 2 (TH2) response. These responses can be discriminated on the basis of cytokine production, such as IFN-γ, which is produced by TH1 cells, and IL-4, which is produced by TH2 cells. The aim of the study was to establish whether the LLNA was sufficient to not only identify allergens but also mark them as either a contact or a respiratory allergen. To this end, LLNA responses to the contact allergen dinitrochlorobenzene (DNCB) and the respiratory allergen trimellitic anhydride (TMA) were determined using IFN-γ and IL-4 mRNA expression and production as parameters. Topical application of TMA resulted in a threefold higher lymphocyte proliferation compared to DNCB 3 and 5 days after the first application, while a similar proliferation was found from Day 7 and onward. RT-PCR showed a similar induction of IFN-γ and IL-4 mRNA expression. While both DNCB and TMA induced IFN-γ production, TMA but not DNCB induced IL-4 production. Thus, only IL-4 production seemed a suitable parameter to discriminate between the two compounds. In a second study, the respiratory allergens toluene-2,4-diisocyanate (TDI) and phthalic anhydride (PA) were also assayed 7 days after the first application. Topical application of DNCB and PA resulted in a similar lymphocyte proliferation, while application of TMA and TDI resulted in a 1.8-fold higher proliferation. IFN-γ production was similar for DNCB, TMA, and TDI, and fourfold lower for PA, while IL-4 production was similar for TMA, TDI, and PA, and 24-fold lower for DNCB. In summary, both studies showed induction of IL-4 production by respiratory allergens, with little or no induction by the contact allergen, holding promise for the possibility of identifying respiratory allergens within the LLNA by measuring IL-4 production 7 days after the first application.

Improvement of lichen nitidus after topical dinitrochlorobenzene application

Recently, a relationship between immunologic alterations and the development of lichen nitidus (LN) lesions has been described. We treated LN lesions with topical dinitrochlorobenzene (DNCB) application in a patient with peripheral CD4 + T lymphocytopenia. After 4 months, the eruption cleared. We investigated histologically and immunohistochemically biopsy specimens obtained before and after treatment. Our result suggests that local alterations of the pattern of cells and cytokines by topical DNCB application could have contributed to the resolution of the LN lesions.(J Am Acad Dermatol 1998;39:305-8.)

T-cell evaluation in patients with colon cancer: dinitrochlorobenzene skin testing versus plasma levels of sIL-2r and sCD8.

Developing reliable methods to test the T-cell system may be important in the treatment of colon cancer patients with 5-fluorouracil/levamisole. In a pilot study we explored whether DNCB (dinitrochlorobenzene) skin testing correlated with plasma levels of soluble interleukin-2 receptor (sIL-2r) and soluble CD8 (sCD8) and, secondly, whether the application of DNCB had any influence on the production of sIL-2r and sCD8. In 10 patients with advanced colon cancer and in 10 healthy volunteers, plasma levels of sIL-2r and sCD8 were measured before and 10 days after the application of 2 mg DNCB on the inner side of the forearm. As expected, colon cancer patients showed a depressed immune system compared to healthy volunteers (DNCB skin test: P = .005, sIL2r [medians 700 vs 295, P = .002], sCD8 [medians 158 vs 90, P = .03], M-W test). The plasma levels for sIL-2r and sCD8 were significantly lower in the skin-positive cases (P = .01 and P = .03, M-W test). However, a large overlap in plasma levels could be observed between the two skin categories. DNCB had no influence on the production of sIL-2r and sCD8; median change skin-negative and skin-positive -10 vs +25, P = .14, respectively; 48 vs 0, P = .32 (M-W test). DNCB skin testing and plasma levels of sIL-2r and sCD8 seem to be equally useful in evaluating the T-cell system and can be used simultaneously.

Improved results of delayed-type hypersensitivity skin testing in HIV-infected patients treated with topical dinitrochlorobenzene

Background: Infection with HIV results in progressive deterioration of cell-mediated immunity, with consequent impairment of delayed-type hypersensitivity (DTH) skin reactivity. Topical dinitrochlorobenzene (DNCB) is thought to increase cellular immune function in HIV infection. Objective: Our goal was to evaluate changes in DTH skin reactivity of HIV-infected patients who were given DNCB therapy. Methods: DTH skin testing and lymphocyte subset analysis were performed in five HIV-infected patients before the start of DNCB treatment and after 3 months of therapy. Topical DNCB application was carried out by the patients according to a standardized protocol. Results: DNCB therapy enhanced DTH skin test responses in four of five patients. Three patients who were anergic before the start of treatment reacted to skin test antigens while using DNCB. The skin test results did not correlate with lymphocyte subset changes. Conclusion: DNCB treatment improves DTH skin test responses in HIV-infected patients, indicating a positive effect on cellular immune function.

Clinical and immunologic evaluation of HIV-infected patients treated with dinitrochlorobenzene.

Promotion of cell-mediated immunity appears to be an important goal in the control of HIV infection. Topical dinitrochlorobenzene (DNCB) stimulates systemic cell-mediated immunity via the induction of cutaneous delayed-type hypersensitivity. Our goal was to evaluate the clinical and immunologic effects of chronic DNCB application in a group of 24 HIV-infected patients. We observed the patients for a mean of 28 months (range, 14 to 44 months). Of the 24 patients, 13 continued weekly DNCB application throughout the study (the compliant group), and 11 discontinued DNCB use after a mean of 10.9 months (the noncompliant group). Two of the 13 compliant patients progressed to AIDS; none of these patients died. In contrast, AIDS developed in 5 of the 11 noncompliant patients and four of these patients died. Analysis of lymphocyte subsets revealed significant increases in natural killer cells and activated/cytotoxic CD8 T-cell subsets in the compliant group. In contrast, these cellular immune-related lymphocyte subsets decreased in the noncompliant subjects. Although CD4 T-cell levels decreased in both groups, there was a significantly greater drop in the noncompliant patients. CD8+CD38+ T cells increased significantly in both groups. Chronic DNCB application appears to have a beneficial clinical and immunomodulatory effect in HIV-infected patients.

Immune Response to other Agents of Calves Persistently Infected with Bovine Virus Diarrhoea Virus (BVDV)

The ability of calves persistently infected (PI) with bovine virus diarrhoea virus BVDV to respond immunologically to defined antigens other than BVDV was studied. Five clinically healthy PI calves were studied together with 5 non-PI calves serving as controls. The humoral immune response was tested by measuring the serum antitoxin titre following immunization against tetanus. The cellular immune response was tested by the ability to develop a positive reaction in a cutaneous tuberculin test performed 1 month after immunization against Johne's disease (paratuberculosis). Finally, a skin-sensitizing agent, dinitrochlorobenzene (DNCB), was employed to study whether PI calves would react by hypersensitization following skin exposure to DNCB for 7 consecutive days followed by application of DNCB to a new skin area remote from the area that had first been exposed. The response of PI calves to the various types of antigenic stimuli applied was not significantly different from that of the control calves. Thus, PI calves developed a potent antitoxin response after tetanus immunization, they showed a positive reaction to tuberculin skin test after immunization against paratuberculosis, and were skin sensitized with DNCB.

Pilot study of topical dinitrochlorobenzene (DNCB) in human immunodeficiency virus infection

Dendritic cells, the primary antigen presenting cells of the human immune system, are heavily infected with human immunodeficiency virus (HIV) in patients with the acquired immunodeficiency syndrome (AIDS). Dinitrochlorobenzene (DNCB) is a contact sensitizing agent that acts as a potent immune modulator of dendritic cells. In this pilot study, we examined the safety and efficacy of topical DNCB application in patients with early HIV disease. Topical DNCB was well tolerated by these patients, with an adverse reaction rate of 10%. CD4 + T-cell counts remained stable with repeated DNCB use. In contrast, CD8 + T-cell counts and natural killer cells increased significantly following DNCB sensitization. This increase in CD8 + T-cell and natural killer cell subsets was accompanied by a decrease in HIV replication, as measured by serum HIV RNA levels. Based on this pilot study, we conclude that topical DNCB is safe in early HIV disease and may decrease viral load via a systemic effect on dendritic cells, CD8 + T-cells and natural killer cells. These results require confirmation in larger controlled trials.

Activation of the Human Immunodeficiency Virus Type 1 Long Terminal Repeat by Skin-Sensitizing Chemicals in Transgenic Mice

Topical dinitrochlorobenzene (DNCB) is often used for evaluating contact skin hypersensitivity in immunocompromised patients. We have determined, in this study, that topical application of DNCB alone, even without induction of contact skin hypersensitivity, was sufficient to observe activation of the human immunodeficiency virus promoter (long terminal repeat) in the skin of an HIV-1 long terminal repeat-luciferase transgenic mouse model. Such treatment might be contra-indicative in patients infected with the human immunodeficiency virus, because in earlier studies DNCB-exposed skin dendritic cells might migrate into draining lymph nodes which play an important role in AIDS pathogenesis.