Predominance of “memory” T cells (CD4+, CDw29+) over “naive” T cells (CD4+, CD45R+) in both normal and diseased human skin

Summary Absolute numbers of CD3+ T lymphocytes and their subpopulations were determined and statistically evaluated in the lesional skin of psoriasis, atopic dermatitis, nummular dermatitis, pityriasis rosea, and lichen planus. Skin sections were divided into horizontal layers and the numbers of CD3+ T cells as well as CD4+ inducer and CD8+ suppressor-cytotoxic T-cell subsets were counted. In addition, absolute numbers of the two subpopulations of inducer T cells, i.e., memory (4B4+ 2H4-) and naive (4B4- 2H4+) were evaluated. Unexpectedly, epidermal infiltration by T cells was highest in psoriasis and lowest in atopic dermatitis. In most cases, this exocytosis was dominated by CD8+ suppressor/cytotoxic T lymphocytes, with a minimal epidermal mean CD4/mean CD8 ratio of 0.04 in pityriasis rosea and a maximum of 0.48 in psoriasis. Inducer T cells within the epidermis were almost exclusively of the 4B4+ 2H4- memory T-cell subpopulation, whereas 4B4- 2H4+ naive T cells were extremely uncommon in lesional epidermis. Similar results were obtained for dermal T cells in all diseases studied, i.e., 4B4- 2H4+ naive T cells were relatively rare. Papillary dermis infiltration by T cells was highest in lichen planus where a mean CD4/mean CD8 ratio of 1.10, the minimum in this comparative study, was obtained. The mean CD4/mean CD8 ratio of the papillary infiltrate was highest in atopic dermatitis (4.12). Our results indicate disease-specific and significantly different infiltration patterns of T-lymphocyte subsets in the chronic inflammatory dermatoses investigated. The predominant presence of the CD4+ 2H4- memory subpopulation of CD4+ T cells in all diseases studied as well as in normal human skin (reported previously) seems to indicate that the skin immune system is rather unidirectional in its increase in this subpopulation of the inducer T-cell subset. This predominance of the memory subpopulation thus indicates that most T cells of normal and diseased human skin are already primed, i.e., have already met their specific ligand in a MHC II context.     

Immunophenotyping of the cellular infiltrate in the early elicitation phase of contact dermatitis in the skin of presensitized atopic individuals

Litte is known about the composition of the cellular infiltrate in the early elicitation phase of contact allergy in atopic individuals. Therefore, we rechallenged ten presensitized disease-free atopic volunteers with their known contact allergen and performed biopsies at time 0 and after 6 and 24 h. Ten patients with acute exacerbated atopic dermatitis in the early stage were chosen as a control group. Skin biopsy specimens were processed for immunohistochemistry (APAAP) and evaluated by computer-assisted morphometry. CD4⁺ and CD45R0⁺ cells were found to be significantly increased after 6 (t₆) and 24 h (t₂₄), and this was accompanied by an enhanced TCR / receptor expression at t₆-CD45O⁺ cells showed a marked influx into the epidermis at t₂₄. CD8⁺ cells infiltrated the basal layer of the epidermis, thus changing the CD4/CD8 ratio from 4.61 at t₀ to 2.21 at t₆. CD1a⁺ epidermal dendritic cells increased significantly from 811 ± 240/mm² at t₀, to 1210 ± 333/mm² at t₂₄ (P<0.01). At t₆ and t₂₄, a socalled epitope CD1a⁺ shedding was observed into the intercellular spaces of keratinocytes as well as an elongation and enlargement of the dendrites of CD1a⁺ cells. In the upper dermis, the number of CD1a⁺ cells increased from 1098 ± 485/mm² at t₀ to 2388 ± 740/mm² at t₂₄ (P<0.01). In 7/10 volunteers, IgE⁺ dendritic cells increased significantly in number at t₆ (P<0.02). The activation markers HLA-DR and CD25 were expressed most distinctly at t₂₄. Interestingly, expression of ICAM-1 on keratinocytes occurred only in four of the ten atopic volunteers. In general, the early elicitation phase of allergic contact dermatitis in atopy is characterized mostly by the same events as seen in non-atopies; however, the lower expression of ICAM-1 on keratinocytes and the increase in IgE-bearing dendritic cells seem to be characteristic for atopic individuals with contact allergy in the early phase after rechallenge with a contact allergen.     

系统性硬皮病CD4~+ T细胞中CD70 mRNA及蛋白表达水平的观察

目的:研究系统性硬皮病(SSc)患者外周血CD4+ T细胞中CD70的表达水平。方法:应用密度梯度离心法分离17例SSc患者(女性12例,男性5例)和13例对照者(女性8例,男性5例)的外周血单个核细胞,磁珠分选CD4+ T细胞。RT-PCR检测CD4+ T细胞中CD70 mRNA的表达水平;流式细胞术检测CD70蛋白在CD4+ T细胞的表达水平。结果:与对照组相比,SSc患者CD4+ T细胞中CD70mRNA和CD70蛋白表达均明显升高(P=0.001;P=0.007)。结论:CD70在SSc的发生发展中可能起着重要作用。     

银屑病患者体外系统血液固有免疫反应中CD4~+ CD25~+ T细胞及CD4~+ CD25~(high) T细胞的变化与意义

目的用体外系统血液固有免疫反应体系研究银屑病患者外周血CD4+ CD25+T细胞及CD4+ CD25highT细胞的变化,并探讨其在银屑病发病机制中的作用。方法将灭活大肠杆菌悬液(3×108/mL)0.2mL作为免疫原激活剂加入枸橼酸抗凝的全血细胞悬液0.2mL和血浆0.3mL中,37℃水浴1h,用流式细胞仪测定CD4+ CD25+T细胞及CD4+ CD25highT细胞的比例。结果在加入大肠杆菌的银屑病全血细胞组(银屑病实验组)CD4+ CD25highT细胞比例(1.88%)明显高于银屑病对照组(1.41%)(P﹤0.01),CD4+ CD25+T细胞及CD4+ CD25highT细胞的比例(16.86%,1.88%)明显低于加入大肠杆菌的健康实验组(24.26%,2.81%)(P﹤0.01);银屑病对照组CD4+ CD25+T细胞及CD4+ CD25highT细胞的比例(15.97%,1.41%)较健康对照组明显降低(21.75%,2.17%)(P﹤0.01);健康实验组CD4+ CD25+T细胞及CD4+ CD25highT细胞的比例群(24.26%,2.81%)均明显高于健康对照组(21.75%,2.17%),(P﹤0.05)。结论银屑病患者CD4+ CD25+T细胞及CD4+ CD25highT细胞比例降低,外来抗原刺激后比例升高,但与健康正常人存在差异。这可能与其复杂的系统免疫学发病机制相关。     

寻常型银屑病患者外周血CD4~+CD25~+及CD8~+CD25~+细胞的检测

目的研究进展期寻常型银屑病患者外周血CD4+CD25+和CD8+CD25+调节性T细胞的数量变化及其在银屑病免疫病理学发病机制中的作用。方法应用流式细胞术对进展期寻常型银屑病患者外周血CD4+CD25+和CD8+CD25+调节性T细胞进行检测。结果进展期寻常型银屑病外周血CD4+CD25+细胞及CD8+CD25+调节性T细胞数量与正常对照组相比,均显著降低(P<0.05,P<0.005),而CD4+CD25+/CD8+CD25+比值无显著性差异(P>0.05)。结论寻常型银屑病的发病与CD4+CD25+和CD8+CD25+调节性T细胞的同步降低有关,与二者的比值无关。     

Characterization of grass pollen reactive T-cell lines derived from lesional atopic skin

Summary Since it has been hypothesized that atopic dermatitis represents a cellular immune reaction to exogenous aeroallergens, we investigated whether lesional skin contains allergen-specific T-cells and which lymphokines they might secrete. Using phytohaemagglutinin or grass pollen for the cloning procedure, we established a series of T-cell lines from the skin of two patients. When rechallenged with the allergen, three out of 12 dermal lines which had been cloned with the pollen extract and three out of 20 epidermal lines cloned with PHA were found to proliferate specifically. With one exception, allergen-specific lines were CD4+, CD8–, / receptor +. The reaction pattern to the single components of the grass allergen extract was assessed with the line UH-D3. Further, the proliferative response to Lolium perennis was inhibited by HLA-DR antibody, indicating its dependence on structures of the MHC class II complex. Only one out of four CD4+ allergen-reactive lines secreted considerable interferon- activity but all secreted interleukin-4. The relative predominance of IL-4 points to a possible role of skin-derived T-cells in the synthesis of IgE. The identification of allergenspecific T-cells in lesional skin of patients with atopic dermatitis is consistent with the hypothesis that their dermatitis represents a T-cell-mediated immune reaction.Part of the work was presented at the Arbeitsgemeinschaft für Dermatologische Forschung, Hamburg 1989     

Increased frequency of intracellular interleukin (IL)-13 and IL-10, but not IL-4, expressing CD4+ and CD8+ peripheral T cells of patients with atopic dermatitis

BACKGROUND: A number of studies exist demonstrating the increased expression of type 2 cytokines and decreased capacity to produce interferon-gamma (IFN-gamma) in peripheral blood mononuclear cells (PBMCs) of patients with atopic dermatitis (AD). OBJECTIVES: To clarify the results of recent studies concerning the role of interleukin (IL)-4 and IL-13 in PBMCs of AD patients, we analysed the activation status of lymphocyte subpopulations. METHODS: We measured the intracellular expression and serum levels of certain type 1 and type 2 cytokines, using cell surface and intracellular cytokine staining, flow cytometry and enzyme-linked immunosorbent assay techniques. RESULTS: The frequency of IL-10 and IL-13 producing CD4+ and CD8+ T cells was significantly higher in patients with AD, while the frequency of IFN-gamma secreting helper and cytotoxic T cells was significantly lower in patients with AD than in control subjects. The serum levels of IL-10 and IL-13 were also significantly increased. There were no significant differences observed between the experimental groups in the frequency of IL-4 producing CD4+ and CD8+ cells. CONCLUSIONS: This study demonstrates a type 2 cytokine production in the CD4+ and CD8+ T cells of AD patients, which is characterized by an elevated IL-13, but not by IL-4 secretion, and by an increased level of the immunoregulatory IL-10, which can contribute to a decrease in IFN-gamma expression.     

Effect of dihomogammalinolenic acid and its 15-lipoxygenase metabolite on eicosanoid metabolism by human mononuclear leukocytes in vitro: selective inhibition of the 5-lipoxygenase pathway

Summary The purpose of the present study was to determine the effect of the n-6 fatty acid, dihomogammalinolenic acid (DGLA, 203, n-6) on arachidonic acid (AA) (C204) metabolism by human peripheral mononuclear leukocytes (HPML). After incubation of HPML with A23187 (5 M) and DGLA, the cyclooxygenase (CO) and lipoxygenase (LO) products were separated and quantified by reversed-phase high-performance liquid chromatography (RP-HPLC) combined with radioimmunoassay. DGLA led to no change in PGE₂ formation, but at similar concentrations there was a dose-dependent decrease in LTB₄ formation (IC₅₀=45.0 M). The inhibition of LTB₄ formation by DGLA was associated with a dosedependent increase in its 15-LO metabolite 15-hydroxyeicosatrienoic acid (15-HETrE) and its CO metabolite prostaglandin E₁ (PGE₁). Incubation of HPLM with 15-HETrE (0–1.5 M) alone did not result in a change in PGE₂ formation, whereas 15-HETrE was a much more potent inhibitor of LTB₄ formation (IC₅₀=0.5 M) than DGLA. These results show that the addition of DGLA to HPML results in a selective inhibition of LTB₄ formation, presumably via its metabolite (15-HETrE).     

CD4~+ CD25~+调节性T细胞与IL-17在梅毒血清固定患者外周血中的表达及意义

目的:观察梅毒血清固定患者外周血中CD4+CD25+调节性T细胞和IL-17的表达及意义。方法:采用三色流式细胞术及免疫酶联吸附法测定18例梅毒血清固定患者和18例对照者外周血中CD4+CD25+调节性T细胞和IL-17的表达水平。结果:梅毒血清固定患者外周血CD4+CD25+调节性T细胞的含量明显高于对照组(t=6.29,P<0.01);IL-17的含量与对照组比较差异无统计学意义(t=-1.68,P=0.102)。结论:CD4+CD25+调节性T细胞表达水平增高造成的免疫抑制可能与梅毒血清固定有关;IL-17的表达水平可能与梅毒血清固定无关。     

Expression of dipeptidyl-peptidase IV (CD26) on CD8+ T cells is significantly decreased in patients with psoriasis vulgaris and atopic dermatitis

T cells play a major role in inflammatory skin disorders such as psoriasis vulgaris and atopic dermatitis. They are both active on the level of cell-to-cell interaction and by the secretion of pro-inflammatory mediators. CD26 is a lymphocyte membrane-associated dipeptidyl peptidase IV (DPP IV), which is able to inactivate chemokines such as RANTES or eotaxin by cleaving dipeptides from the NH2-terminus of proteins. We investigated the expression of CD26 on CD4+ and CD8+ peripheral blood T cells in patients with psoriasis and atopic dermatitis. In addition PASI and SCORAD as a measure of disease severity were determined in each patient at the time of blood drawing. Thirty patients with psoriasis, 15 with atopic dermatitis and 17 age- and sex-matched healthy persons were investigated by two-colour flow cytometry using epitope-specific monoclonal antibodies. Our results revealed, that there is a significant decrease (P<0.05) of CD26 expression on CD8+ T cells in both psoriasis (7.7%+/-3.3, mean and SD, n=30) and atopic dermatitis patients (7.9%+/-3.7, mean and SD, n=15) compared to the control population (11.58%+/-5.0, mean and SD, n=17). However, there was no correlation to disease severity as determined by PASI and SCORAD, respectively. Since CD26 can be regarded as an anti-inflammatory principle the decreased expression in psoriasis and atopic dermatitis patients may lead to a dysbalance in favour of pro-inflammatory mediators in both clinical conditions.     

Bound lipids liberated by alkaline hydrolysis after exhaustive extraction of pulverized clavus

In the present study, covalently bound lipids were found in clavus material and their lipid classes were determined by high-performance thin-layer chromatography (HPTLC). Clavus material, pulverized completely in a Mikro-Dismembrator II, was exhaustively extracted three times with chloroform/methanol (21, 11 and 12 v/v) at 80C for l h each time and this sequence of extractions was repeated to obtain the unbound lipid-free residue which was saponified and then extracted with chloroform. The extract proved to comprise several bands of lipids covalently bound through an ester-like linkage. These were identified as free fatty acids, cholesterol, ceramides and glucocerebrosides by HPTLC. However, -hydroxy fatty acids were not detected in the lipids. To analyse the fatty acids amide-linked to the bound ceramides, the latter were isolated by preparative HPTLC and subjected to mild acid hydrolysis. Since the bound ceramides constituted neither -hydroxy fatty acids nor -hydroxy fatty acids, they were not identified as hydroxyl-acylsphingosines.     

特应性皮炎患儿血清和CD4+CD25+ T细胞分泌IL-10水平的检测

目的 探讨儿童特应性皮炎血清和CD4+CD25+T分泌细胞因子IL-10表达,分析其与病程及严重程度的相关性。 方法 特应性皮炎患儿按SCORAD指数分3组,轻度10例、中度16例、重度20例。抽取46例特应性皮炎患儿和31例健康对照儿外周血,用免疫磁珠分离获得CD4+CD25+T细胞,用ELISA法分别检测患病组和健康对照组血清及CD4+CD25+T细胞培养液IL-10水平,并分析IL-10水平与SCORAD评分的相关性。结果 轻、中、重度AD各组血清IL-10水平分别为（43.10 ± 25.07）、（68.40 ± 36.65）、（55.55 ± 41.97） pg/ml,与健康对照组（58.27 ± 36.84） pg/ml比较,差异均无统计学意义（P ＞ 0．05）,与患儿SCORAD评分无相关性。轻、中、重度AD组CD4+CD25+T细胞分泌IL-10含量分别为（52.96 ± 11.69）、（49.86 ± 9.18）、（27.25 ± 7.01） pg/ml,重度AD组低于健康对照组（55.15 ± 11.15） pg/ml （P < 0．05）;轻、中度组与健康对照组差异无统计学意义（P ＞ 0．05）。CD4+CD25+T细胞分泌IL-10的水平与患儿疾病严重程度SCORAD评分呈明显负相关（r值分别为-0．757,P < 0．01）。结论 CD4+CD25+T细胞及相关因子IL-10可能参与儿童特应性皮炎的发病。     

Decreased total numbers of peripheral blood lymphocytes with elevated percentages of CD4+CD45RO+ and CD4+CD25+ of T-helper cells in non-segmental vitiligo

Vitiligo is a disorder involving progressive skin depigmentation caused by host mediated destruction of melanocytes. Its pathogenesis is known to correlate with elevated levels of activated skin-infiltrating T lymphocytes and is presumed to be autoimmune in nature. In the present study, we characterize the immunophenotype of peripheral blood T cells from vitiligo patients, with the objective of developing an investigative and diagnostic tool for the disease, using analysis of peripheral blood. Subjects for this investigation included 32 patients diagnosed with non-segmental vitiligo and 28 age-and gender-matched, normal, healthy control participants. Whole venous blood taken from each subject was analyzed using 2-color flow cytometry for immunologically-relevant lymphocyte subsets. When compared with healthy control subjects, peripheral blood from individuals with vitiligo was found to have lower total numbers of lymphocytes (p<0.039). Vitiligo patients also had elevated percentages of memory (CD4+CD45RO+) T cells; (p<0.05), but NK-T cells (CD3+CD16+CD56+) and naive T cells (CD4+CD45RA+) were present at lower total numbers and percentages than in healthy controls (p<0.01 and 0.05 respectively). Blood from severely afflicted subjects exhibited elevated CD3+HLADR+ and CD4+CD45RO+ as well as lower percentages of NK-T cells (p<0.05) when compared with mild cases. In conclusion, disease-associated, peripheral blood lymphocyte immunophenotypic profiles of vitiligo patients are consistent with the hypothesis of T cell activation as a major feature of the disorder. These include elevated memory and reduced naive T cell percentages and increased expression of the activation-associated surface antigen CD25. These changes presumably reflect increased antigen-mediated activation. Moreover, because a corollary effect is increased activation-induced cell death (AICD), lower overall lymphocyte counts observed in vitiligo-afflicted subjects is also expected.     

Caspase抑制剂对特应性皮炎患者外周血CD4+T细胞亚群分泌细胞因子的影响

目的：明确广谱半胱氨酸天冬氨酸蛋白酶(caspase)抑制剂对特应性皮炎(AD)患者外周血CD4+T细胞亚群分泌细胞因子的影响。方法：广谱caspase抑制剂Z-VAD-FMK与30例AD患者外周血单一核细胞(PBMCs)体外共培养后,PBMCs分为3组,分别加入Z-VAD-FMK溶液、地塞米松溶液和PBS溶液。流式细胞仪检测CD4+T细胞亚群;ELISA方法检测上清液中IFN-γ、IL-4、IL-17的浓度。结果：IFN-γ、IL-4、IL-17水平在PBS溶液组高于Z-VAD-FMK组,差异均有统计学意义(均P<0.01),在Z-VAD-FMK组与地塞米松组间比较,均无统计学意义(均P>0.05)。结论：广谱caspase抑制剂Z-VAD-FMK可抑制AD患者PBMC中CD4+T细胞Th1、Th2、Th17分泌相关细胞因子。     

Candida albicans-specific lymphoproliferative and cytokine (IL-4 and IFN-gamma) responses in atopic eczema dermatitis syndrome. Evidence of CD4/CD8 and CD3/CD16+CD56 ratio elevations in vitro

BACKGROUND: Hypersensitivity to cross-reactive mannan polysaccharide allergens of saprophytic yeasts is likely to be involved in the pathogenesis of atopic eczema dermatitis syndrome (AEDS). Mannans induce elevated specific immunoglobulin E and lymphoproliferative responses in peripheral blood mononuclear cells (PBMCs). To gain more detailed data of the involvement of different subpopulations of PBMCs in AEDS after mannan stimulation, changes in the cell-surface marker distribution were analysed. METHODS: The Ficoll-isolated PBMCs of eight yeast hypersensitive AEDS patients and seven non-AEDS controls were stimulated in vitro by mannan (CAM) or whole extract antigen [In-House Reference (IHR)] of Candida albicans or tuberculin [purified protein derivative (PPD)] and after immunofluorescence staining analysed by flow cytometry. The expression of cytokine mRNA was measured by kinetic real-time polymerase chain reaction (TaqMan). RESULTS: After 7-day antigen stimulation, there were significant increases in the CD3/CD16(+)CD56 ratio (P = 0.028 with mannan and P = 0.006 with IHR), CD4/CD8 ratio (P = 0.049 with mannan) and interleukin-4/interferon-gamma (IL-4/IFN-gamma) mRNA ratio (P = 0.028 with IHR) and a decrease in the CD3/CD19 ratio (P = 0.035 with mannan) of AEDS patients' PBMCs as compared with healthy controls' cells. These changes were not seen in cultures with PPD. CONCLUSIONS: The observed CAM and IHR-induced elevations in T cell/natural killer cell, CD4/CD8 and IL-4/IFN-gamma ratios suggest that C. albicans-induced TH(2)-type responses can also play a role in AEDS.     

SLE患者外周血中CD4＋CD25＋CD127^low/-标记的调节性T细胞与临床表现和实验室指标相关性研究

目的：探讨CD4＋CD25＋CD127low/-标记的调节性T细胞（Treg）在系统性红斑狼疮发病机制电的作用。方法：用流式细胞仪检测45例系统性红斑狼疮（SLE）患者和45例年龄、性别相匹配的健康志愿者外周血CD4＋T细胞中Treg的百分比,同时分析SLE患者外周血中的CD4＋CD25＋CD127low/-标记的Treg与其临床表现、实验室指标的相关性。结果：SLE患者外周血CD4＋T细胞中Treg百分比与健康对照组比较差异无统计学意义。在SLE患者中,Treg的百分比与抗核小体抗体呈正相关（r=0．299,P=0．046）,有光敏感的SLE患者中Treg较无光敏感组增高（P=0．017）,余均无统计学差异。结论：SLE患者外周血中以CD4＋CD25＋CD127low/-标记的Treg中可能因含有部分无免疫抑制活性的效应性T细胞而特异性差,因此可能不适合用于临床免疫抑制治疗。     

斑秃患者外周血T淋巴细胞亚群及CD4~+CD25~+调节T细胞的检测

目的检测斑秃(AA)患者外周血T淋巴细胞亚群及CD4+CD25+调节性T(Tr)细胞数量变化,分析AA的可能病因。方法利用流式细胞仪和单克隆荧光抗体技术,测定重度和局限性AA各40例患者外周血中T淋巴细胞亚群占T淋巴细胞的比率及CD4+CD25+Tr细胞在CD3+CD4+T淋巴细胞中的比率。结果重度AA患者外周血中CD4+CD25+Tr细胞占CD3+CD4+T细胞的比率为(1.43±0.74)%,显著低于正常对照组(2.25±0.97)%(P<0.01),重度AA患者的CD4+T占T淋巴细胞的比率为(31.42±6.66)%,略高于正常对照组(30.69±7.47)%(P>0.05),差异无显著性,而CD8+T占T淋巴细胞的比率为(25.86±4.35)%,明显高于正常对照组(22.42±6.10)%(P<0.01);局限性AA患者的三项指标分别为(2.14±0.87)%,(32.60±10.27)%和(21.59±5.24)%,与对照组差异无显著性(P>0.05)。结论AA患者外周血中CD4+CD25+Tr明显低于正常对照组,CD8+T比率明显高于正常对照组,可能是导致重度AA发病的主要免疫机制。     

Severe atopic dermatitis is associated with a reduced frequency of IL-10 producing allergen-specific CD4+ T cells

BACKGROUND: Several studies have investigated levels of T-cell-derived interleukin (IL)-10 in individuals with atopic dermatitis, with conflicting results. AIMS/HYPOTHESIS: In order to address whether stratification of disease severity may help resolve the different findings, the hypothesis was tested that individuals with severe atopic dermatitis have a lower frequency of circulating IL-10-producing, allergen-specific CD4+ T cells than do individuals with mild disease. METHODS: Using peripheral blood mononuclear cells derived from individuals with severe (n=12) and mild atopic dermatitis (n=10) and from nonatopic controls (n=10), we investigated production by CD4+ T cells of tumour necrosis factor (TNF)-alpha, IL-4, IL-5, IL-13 and IL-10 in response to phorbol myristate acetate/ionomycin and Der p1 allergen. RESULTS: It was observed that there were significantly higher frequencies of allergen-specific circulating CD4+ T cells producing TNF-alpha- IL-4-, IL-5- and IL-13, and lower frequencies of these cells producing IL-10 in individuals with severe atopic dermatitis compared with mildly affected individuals and nonatopic controls (P<0.01 for all comparisons). Furthermore, the Der p1-specific CD4+ T cells were enriched within the subset of cells positive for cutaneous lymphocyte-associated antigen. CONCLUSIONS: Analysis of levels of allergen-specific CD4+ T-cell production of IL-10 in relation to disease severity argues in favour of a role for IL-10 in the control of atopic dermatitis.