Detection and Analysis of Commonly Used Infection Indicators in Patients with Acute Urticaria.

INTRODUCTION: In this study, we investigated the correlation and clinical significance of peripheral blood leukocytes, neutrophils, C-reactive protein (CRP), and procalcitonin (PCT) in patients with acute urticaria. METHODS: Complete blood count with differential, CRP, and PCT tests were conducted on patients with acute urticaria. A total of 614 patients with acute urticaria were divided into three groups: the first group consisted of patients with elevated leukocyte and neutrophil count, the second group consisted of patients with normal leukocyte and neutrophil count, and the third group consisted of patients with abnormal leukocyte and neutrophil count. A correlation analysis was conducted to investigate the levels of leukocytes, neutrophils, CRP, and PCT in the three groups. RESULTS: The results of Kruskal-Wallis' nonparametric test revealed statistically significant variations in leukocytes, neutrophils, CRP, and PCT among the three groups (p < 0.001). However, CRP and PCT showed no statistically significant differences between the second and third groups (p < 0.001, p = 0.0041, p = 0.0032). Additional multiple comparisons in Spearman correlation analysis indicated statistically significant differences (p = 0.55). Across all groups, there was a statistically significant difference in the correlation between CRP-PCT and leukocytes-neutrophils (p = 0.53). CONCLUSION: Leukocytes and neutrophils are sensitive to the impact of medications and stress on the body. Combining CRP and PCT, as well as routine blood test, may be a comprehensive assessment of infection presence and severity in patients, providing guidance for antibiotic treatment.

Correlation between double-stranded DNA and acute urticaria.

BACKGROUND: Acute urticaria is a prevalent inflammatory dermatosis characterized by fulminant wheals, often accompanied by severe pruritis. It may also cause nausea, vomiting, and abdominal pain. Numerous studies have substantiated the pivotal involvement of double-stranded DNA (dsDNA) in autoimmunity. However, the role of dsDNA in the pathogenesis of acute urticaria is unclear. METHODS: We measured serum dsDNA levels in patients and controls. The relationship between dsDNA levels and environmental exposures (temperature, ultraviolet [UV] index, and season) was investigated by correlating disease onset dates with archived meteorological data. Finally, we used quantitative PCR to determine the expressions of genes encoding dsDNA receptors, single-stranded RNA (ssRNA) receptors, exosome formation, and type I interferon in the peripheral blood of patients and controls. RESULTS: Serum dsDNA levels were significantly higher in patients with acute urticaria compared with controls (mean values 1.38 and 0.94 ng/ml, respectively, P < 0.001). dsDNA levels were higher in patients exposed to higher environmental temperatures and UV indices and were higher during the summer months. We also found that the expressions of genes encoding dsDNA receptors, ssRNA receptors, absent in melanoma factor 2 (AIM2)-related inflammatory factors, and interferon alpha were up-regulated in patients. CONCLUSIONS: We demonstrated that serum dsDNA levels are elevated in acute urticaria and are influenced by climatic factors such as temperature, ultraviolet index, and season. We also found that elevated dsDNA promotes the expression of AIM2-related factors and type I interferons. This study generates new hypotheses regarding the pathogenesis of acute urticaria and suggests novel therapeutic targets.

Hereditary alpha-tryptasemia in 101 patients with mast cell activation-related symptomatology including anaphylaxis.

BACKGROUND: Hereditary alpha-tryptasemia (HαT) is an autosomal dominant genetic trait characterized by multiple copies of the alpha-tryptase gene at the TPSAB1 locus. Previously described symptomatology involves multiple organ systems and anaphylaxis. The spectrum of mast cell activation symptoms is unknown, as is its association with specific genotypes. OBJECTIVE: To describe clinical, laboratory, and genetic characteristics of patients referred for the evaluation of mast cell activation-related symptoms and genotype-confirmed HαT. METHODS: We retrospectively describe clinical characteristics, baseline tryptase, and tryptase genotype in 101 patients. Patients were referred for mast cell activation-related symptoms and underwent genotyping to confirm diagnosis of HαT. RESULTS: Of 101 patients, 80% were female with average tryptase of 17.2 ng/mL. Tryptase was less than 11.4 ng/mL in 8.9% and greater than 20 ng/mL in 22.3% (range 6.2-51.3 ng/mL). KIT D816V mutation was negative in all subjects tested. 2α:3ß was the most common genotype but did not correlate with tryptase levels. Unprovoked anaphylaxis was noted in 57% of the subjects with heterogeneous genotypes. Most common symptoms include gastrointestinal, cutaneous, psychiatric, pulmonary, cardiovascular, and neurologic. A total of 85% of patients were taking H1- or H2-antihistamines with partial symptom relief. Omalizumab was effective at suppressing anaphylaxis or urticaria in 94% of the patients. CONCLUSION: HαT encompasses a broad range of baseline tryptase and should be considered in patients with symptoms of mast cell activation and tryptase levels greater than 6.2 ng/mL. Patients may present with complex symptomatology including cutaneous, gastrointestinal, neurologic, and psychiatric symptoms and anaphylaxis, some of which respond to omalizumab.

miR-126-3p and miR-16-5p as novel serum biomarkers for disease activity and treatment response in symptomatic dermographism.

Symptomatic dermographism (SD) is the most common form of physical urticaria. So far no promising serum biomarkers for SD have been reported. Recently, microRNAs (miRNAs) have been reported to be serum biomarkers for chronic spontaneous urticaria. However, association of miRNAs with SD remains unclear. We enrolled 55 SD patients and 52 healthy controls in this study. We found that serum expressions of miR-126-3p and miR-16-5p were significantly downregulated in active SD patients and upregulated in remission. The area under the curve values of miR-126-3p (0.769) and miR-16-5p (0.789) showed significant ability to diagnostic SD. Serum level of vascular endothelial growth factor (VEGF)-A, a known target of the two miRNAs, was significantly increased in active SD patients and decreased in remission. Moreover, serum VEGF-A level was inversely correlated with expressions of miR-126-3p and miR-16-5p. Our findings indicate that miR-126-3p and miR-16-5p can serve as potential serum biomarkers for SD.

Serum amyloid A levels in acute and chronic urticaria

Abstract: Background: Serum amyloid A is an acute-phase protein. There is no available data regarding serum amyloid A levels in patients with acute and chronic urticaria (CU). Objective: To investigate the association between serum amyloid A and urticaria. Methods: This was a case-control study of 81 patients who visited our Hospital between June and December 2016 with a diagnosis of urticaria. Eighty healthy controls (HC) who visited for routine health examination and physical checkups were recruited. Serum amyloid A and C-reactive protein levels were measured by automated methods. Results: Serum amyloid A and C-reactive protein levels were significantly higher in AU (Serum amyloid A: 207.1 (6.7-439.0) mg/L; C-reactive protein: 16.0 (0.2-90.0) mg/L) and CU (Serum amyloid A: 6.5 (2.5-35.8) mg/L; C-reactive protein: 1.0 (0.1-16.0) mg/L) compared with HC (Serum amyloid A: 5.04 (2.0-9.1) mg/L; C-reactive protein: 1.2 (0.1-5.6) mg/L), and in AU compared with CU (all P<0.05). There were no differences between the CU and HC group. In CU, Serum amyloid A levels in those with moderate/severe urticaria (median, 16.4 (9.7-35.8) mg/L) were higher than in those with mild urticaria (median, 5.7 (2.5-9.5) mg/L) and HC (all P<0.05). Serum amyloid A and C-reactive protein levels exceeded the normal lab range in 90.7% and 72.1% patients with AU compared with 28.9% and 13.2% patients with CU, respectively. Significant positive correlations were found between serum amyloid A and C-reactive protein (r = 0.562, P < 0.001). Study limitations: There was no comparison between active disease and remission. Conclusion: There was an association between serum amyloid A levels and urticaria. Higher serum amyloid A levels were associated with AU and more severe CU. Serum amyloid A may help to identify CU patients earlier.

Serum miR-125a-5p and CCL17 Upregulated in Chronic Spontaneous Urticaria and Correlated with Treatment Response.

Chronic spontaneous urticaria (CSU) is a common skin disorder associated with autoimmunity. MicroRNAs (miRNAs) are endogenous noncoding RNA molecules reported to be potential biomarkers for some autoimmune diseases. In this study, we investigated the association of miRNAs with CSU. A quantitative PCR (qPCR)-based array was generated from sera as obtained from 20 active CSU patients and 20 healthy controls. Upregulated or downregulated miRNAs were validated by reverse transcription qPCR in sera from 59 active CSU patients and 58 healthy controls. The expression of miR-125a-5p was significantly upregulated in CSU sera and serum levels of CCL17 were also significantly increased in CSU patients. Serum miR-125a-5p expressions were found to be further upregulated in refractory CSU cases (n = 10). In 12 CSU patients in remission, serum miR-125a-5p expression and CCL17 levels were significantly decreased as compared with that obtained in active phase patients. These results indicated that miR-125a-5p and CCL17 can serve as potential serum biomarkers for CSU.

The overlap syndrome of urticaria and gastroesophageal reflux disease.

BACKGROUND: One-quarter of systemic symptoms associated with chronic spontaneous urticaria (CSU) are related to gastrointestinal complaints (GICs). OBJECTIVES: To investigate the prevalence and features of urticaria-overlapping GICs. METHODS: In this retrospective cross-sectional survey, 1426 consecutive outpatients were observed at our University Department. Only patients suffering from urticaria or GICs with a complete diagnostic work-up including serum total IgE level (Tot-IgE), differential blood count and urticaria activity score (UAS), were evaluated. RESULTS: Among different GICs, gastroesophageal reflux disease (GERD) was the most frequent syndrome observed (15.4%; 95%CI: 13.6-17.3). The prevalence of overlap syndrome for urticaria and GERD was 5.9% (95%CI: 4.7-7.2). In urticaria-patients, the prevalence of GERD was four-fold higher than in patients without hives (44% vs. 11%, p<0.001). UAS was significantly higher in urticaria and GERD overlap syndromes vs. isolated urticarias. In patients with GERD or acute/chronic urticaria or overlap syndrome, Tot-IgE and eosinophil blood count (EBC) differed significantly, with a stepwise increase in their values; from the subgroup of patients with GERD only, to that with overlap of CSU to GERD. Prevalence values for urticaria overlapping with GERD were three- and two-fold higher in CSU and in long-duration GERD cases respectively compared to acute urticaria or short-duration GERD cases. Similar to Th2 pathology models, CSU and GERD overlap syndrome was significantly and independently associated with Total-IgE ≥100IU/ml or EBC ≥250/mmc compared to CSU or GERD. Endoscopic/bioptic findings of non-erosive reflux disease (NERD) or Barrett's esophagus (BE) were more frequent in chronic overlap syndrome than in GERD-patients. CONCLUSIONS: GERD was the most frequent GIC in patients with urticaria. Overlap syndrome was more frequent among patients with CSU, where this syndrome was associated with higher values of UAS, Tot-IgE, EBC and frequencies of NERD and BE. These results suggest that overlap syndrome is frequently a chronic syndrome with a Th2-like profile.

Post-infectious sensory neuropathy with anti-GT1a and GQ1b antibodies associated with cold urticaria.

A 64 years-old woman presented subacute onset distal paraesthesia concurrently with cold-induced urticaria, a rare form of physical urticaria. Both the disturbances developed a fortnight after an upper respiratory tract infection. EMG confirmed an exclusively sensory polyneuropathy, with prolongation of distal latencies and reduction of amplitudes. Anti-GQ1b and anti-GT1a antigangliosides antibodies were found in serum. The clinical workout included CSF analysis, cryoglobulin and paraprotein search, neurotropic infective agents, neoplastic markers and extensive autoimmune disease antibodies analysis, all of which resulted negative. Intravenous immunoglobulins were administered, leading to progressive resolution of the sensory disturbance, while a combination of steroid and anti-histaminics treatment was used for the urticaria. The positivity for anti-ganglioside search with an EMG pattern characterized by a mixture of demyelinating and axonal features may suggest a nodo-paranodopathy at early stages. This is the first case of an association between an acute sensory neuropathy and cold urticaria, two immune mediated conditions apparently due to very different hypersensitivity pathways. A proposed mechanism for the co-occurence of these two conditions is presented, whereas this case expands the clinical spectrum of autoimmune diseases associated with anti-GQ1b and anti-GT1a antibodies.

Hyperlipidemia in association with pro-inflammatory cytokines among chronic spontaneous urticaria: case-control study.

Summary: Chronic spontaneous urticaria (CSU) is a disorder characterized by recurrent transient itchy wheels of 6 weeks duration or longer. The cause cannot be pinpointed in about 40% of patients. To elucidate the possible association between CSU and hyperlipidemia, 40 CSU patients and 40 group matched healthy individuals were assessed for hyperlipidemia. Data on history, urticaria activity score (UAS-7), physical examination and routine laboratory investigations including (serum IL6 and TNF α) were recorded. Statistically significant increase of serum cholesterol, triglycerides (TG), low density lipoprotein (LDL), IL6, TNFα and decrease of high density lipoprotein (HDL) was found in CSU in comparison to control group. Regarding the different disease variables, both TG and cholesterol were positively correlated with duration of illness, urticaria score and TNF α. Serum LDL detected significant had a positive correlation with duration of illness, urticaria score, CRP and TNF α, while serum HDL detected had a significant negative correlation with TNF α. IL6 and TNFα associated systemic inflammation could be a common pathogenic mechanism of CSU and hyperlipidemia. Patients with CSU should be evaluated for hyperlipidemia.

Circulating soluble LIGHT/TNFSF14 is increased and associated with IL-8 concentration in chronic spontaneous urticaria.

LIGHT (homologous to lymphotoxins, exhibiting inducible expression, and competing with herpes simplex virus (HSV) glycoprotein D for herpes virus entry mediator (HVEM), a receptor expressed by T lymphocytes) has been involved in various autoimmune and inflammatory disorders. LIGHT induces the expression of interleukin-8 (IL-8), which is up-regulated in chronic spontaneous urticaria (CSU). To determine circulating soluble LIGHT concentration and its relationship with IL-8 concentration in patients with CSU. Concentrations of LIGHT, IL-8, and C-reactive protein (CRP) were determined in plasma or serum of CSU patients by an enzyme-linked immunosorbent assay. LIGHT plasma concentration was significantly higher in moderate-severe CSU patients as compared with the healthy subjects, but not with mild CSU patients. There were significant correlations between increased LIGHT and IL-8 concentrations, but not with increased CRP in CSU patients. Enhanced plasma concentrations of soluble LIGHT and its association with IL-8 concentration suggest the role of LIGHT in systemic inflammatory activation in CSU patients. We hypothesize that LIGHT-mediated immune-inflammatory response plays a role in severe phenotypes of the disease.

Epidemiology of hypocomplementaemic urticarial vasculitis (anti-C1q vasculitis).

Objectives: The aim was to describe the clinical characteristics and epidemiology of hypocomplementaemic urticarial vasculitis (HUV; anti-C1q vasculitis) in two geographically defined areas of Sweden. Methods: In the health-care districts surrounding Skåne University Hospital (mean population 950 560) and Linköping University Hospital (mean population 428 503), all incident cases of HUV residing within the study areas at the onset of disease were identified during the years 2000-15. The diagnosis of HUV was confirmed by review of medical records. Only patients meeting the proposed diagnostic HUV criteria and/or the 2012 Chapel Hill consensus definitions in combination with an ever-positive anti-C1q antibody test were included. Results: Sixteen patients (14 females) were identified during the study period. The median (interquartile range) age at diagnosis was 51 (40.7-56.7) years. Median (interquartile range) time of follow-up from diagnosis to 31 December 2015, or death, was 94 (46.5-136.2) months. The most frequent manifestations at diagnosis were urticaria (100%), arthritis (88%), followed by biopsy-proven glomerulonephritis (19%), episcleritis/scleritis (19%) and recurrent abdominal pain (13%). The annual incidence rate per million inhabitants was estimated as 0.7 (95% CI: 0.4, 1.1). Sixty-three per cent suffered from pulmonary disease at the last follow-up. Two patients died during the follow-up period. One patient underwent lung transplantation, and two patients proceeded to end-stage renal disease. The point prevalence on 31 December 2015 was 9.5/million (95% CI: 4.5, 14.5). Conclusion: Hypocomplementaemic urticarial vasculitis constitutes a rare, but not always benign condition. Renal and lung manifestations were severe in some cases, highlighting the need for careful screening and monitoring of this potentially serious condition.

Four cases of acute infectious urticaria showing significant elevation of plasma D-dimer level.

D-dimer, a fibrinolytic end-product, has been regarded as a biomarker indicating the severity of urticaria, especially in chronic urticaria. Regarding acute urticaria, D-dimer level is also suggested to be elevated, which may be significant in comparison with chronic urticaria. However, the clinical features of acute urticaria with concomitant significant elevation of D-dimer level have not been investigated in detail so far. We present four cases of acute urticaria fulfilling the proposed diagnostic criterion of acute infectious urticaria, in which significant elevation of D-dimer level and rapid spontaneous normalization in parallel with the resolution of fever and urticaria occurs. No cases had deep vein thrombosis, disseminated intravascular coagulation and malignancy. All cases responded well to antihistaminic treatment in combination with antibiotics, and their fever and urticaria resolved within 10 days. All cases showed severe wheals persistent for several days resolving with hyperpigmentation. Histologically, infiltration into blood vessel walls and interstitial infiltration of lymphocytes and polymorphonuclear cells were marked in the dermis. In our cases, clinical features accorded with acute infectious urticaria, and their histological features were similar to those of neutrophilic urticaria as described previously. In conclusion, there is a certain group of acute urticaria associated with significant elevation of D-dimer level. These common features of our cases may be characteristic in acute urticaria showing the coagulative and fibrinolytic abnormalities.

Serum carcinoembryonic antigen specifically increases among various serum markers of adenocarcinoma in hypohidrosis or conditions related to hypohidrosis.

Anhidrosis/hypohidrosis are conditions presenting various level of sweating dysfunction. Among them, acquired idiopathic generalized anhidrosis (AIGA) presents inadequate decrease or loss of sweating without apparent neurological and dermatological symptoms except cholinergic urticaria. Recently, serum level of carcinoembryonic antigen (CEA), one of the most well-known tumor markers, has been proposed as a clinical marker reflecting activity of AIGA. This study was performed to verify the specificity and independence of serum CEA level from the other serum tumor markers especially related to adenocarcinoma. The expression of various tumor markers in the serum collected from three healthy control subjects, four AIGA cases, and a cholinergic urticaria (CU) case with elevation of serum CEA level and history of hyperthermia was analyzed using a membrane-based antibody array. In all AIGA and CU cases, the intensity of CEA was significantly increased (7.60-15.9 times compared with that of control), relatively well-reflecting the serum CEA level, and the mean intensity of CEA was 11.8 times higher than the control subjects (P = 0.0011). On the other hand, the ratio of carbohydrate antigen (CA)125 and CA19-9 was 1.93 and 0.23 times compared with the mean intensity of the control subjects, respectively, and there was no statistical significance. Immunohistochemistry on 10 AIGA cases showed increased expression of CEA but not CA19-9 and CA125 in the eccrine sweat glands. In conclusion, the elevation of serum CEA level was independent from the other tumor markers in hypohidrotic condition represented by AIGA.

Potential blood biomarkers in chronic spontaneous urticaria.

Chronic spontaneous urticaria (CSU) is a mast cell-driven disease that is defined as the recurrence of weals, angioedema or both for > 6 weeks due to known or unknown causes. As of yet, disease diagnosis is purely clinical. Objective tools are needed to monitor the activity of CSU and the efficacy of treatment. Recently, several reports have suggested that blood parameters may be considered as potential disease-related biomarkers. Here, we reviewed available literature on blood biomarkers for CSU diagnosis, activity monitoring, duration, patient subgroup allocation or response to treatment. We performed a PubMed, Google Scholar and Web of Science search and identified and analysed 151 reports published prior to January 2016. We found strong evidence for significant differences between patients with CSU and healthy controls in blood levels or values of D-dimer, C-reactive protein (CRP), matrix metalloproteinase-9 (MMP-9), mean platelet volume (MPV), factor VIIa, prothrombin fragment 1 + 2 (F1 + 2), tumour necrosis factor, dehydroepiandrosterone sulphate and vitamin D. Also, there is strong evidence for a significant association between CSU activity and blood levels or values of D-dimer, F1 + 2, CRP, IL-6 and MPV. Strong evidence for reduced basophil count and high levels of IgG anti-FcεRI in the subgroup of CSU patients with positive autologous serum skin test was shown. In contrast, the evidence for all reported blood biomarkers for differentiating CSU from other diseases, or a role in prognosis, is weak, inconsistent or non-existent. Taken together, we identified 10 biomarkers that are supported by strong evidence for distinguishing patients with CSU from healthy controls, or for measuring CSU activity. There is a need for further research to identify biomarkers that predict outcome or treatment response in CSU.

Basophil CD63 expression in chronic spontaneous urticaria: correlation with allergic sensitization, serum autoreactivity and basophil reactivity.

BACKGROUND: The underlying causes and factors contributing to the disease severity of chronic spontaneous urticaria (CSU) are unknown. OBJECTIVE: Given the important role of basophils in the pathogenesis of urticaria and that CD63 serves as a useful marker for basophil activation and detecting, CD63 expression of basophils is a reliable tool for diagnosing allergy and hypersensitivity reactions to different allergens; the objective of this study was to investigate whether the level of basophil CD63 expression is correlated with allergen sensitization, serum autoreactivity and basophil reactivity in patients with CSU. METHODS: Basophil-enriched leucocytes were separated from the blood of 64 patients with chronic urticaria (54 CSU patients and 10 symptomatic dermographism patients), 18 healthy control subjects and seven atopic donors without urticaria. Flow cytometry was then used to detect CD63 expression on the cell membrane of basophils from all samples. Analysis was also preformed on basophils incubated with sera from CSU patients with positive or negative autologous serum skin test (ASST). RESULTS: CD63 expression was significantly higher in the basophils from patients with CSU than in those from patients with symptomatic dermographism and the healthy control group. The levels of CD63 expression in CSU patients with ASST+ and/or allergen sensitization were higher than those with ASST- and/or no allergen sensitization patients. Incubation with ASST+ serum resulted in an increased expression of CD63 in the basophils of ASST+ CSU patients, whereas no such response was observed in healthy controls or ASST- CSU patients. CONCLUSION: The increased CD63 expression in basophils from CSU patients may correlate with allergen sensitization, autoreactivity of serum and basophil reactivity. Our results suggest that CD63 may contribute new insight into the pathogenesis of CSU.

Association of TG2 from mast cells and chronic spontaneous urticaria pathogenesis.

BACKGROUND: Mast cells and their mediators play important roles in chronic spontaneous urticaria (CSU) pathogenesis. Transglutaminase 2 (TG2) is expressed in activated mast cells and contributes to airway inflammation in allergic asthma. OBJECTIVE: To investigate the role of TG2 in CSU. METHODS: Patients with CSU (n = 72) and healthy controls (n = 51) were evaluated. Skin biopsy specimens were obtained from 5 patients with CSU and 2 healthy controls. Cord blood-derived human mast cells and peripheral blood-derived human mast cells were activated with IgE. TG2 activity and inflammatory mediators, such as histamine, leukotriene C4, and cytokines, were measured in serum or supernatant from cultured mast cells by enzyme-linked immunosorbent assay. Colocalization of mast cells and TG2 was determined in skin tissues by immunofluorescence. RESULTS: TG2 activity was significantly higher in serum samples from patients with CSU than in serum samples from healthy controls (P < .001). Colocalization of mast cell surface marker c-kit and TG2 was significantly increased in the lesional skin of patients with CSU compared with that in healthy controls. The levels of histamine, leukotriene C4, tumor necrosis factor α, transforming growth factor ß, and interleukins 4, 5, and 6 were significantly higher in patients with CSU than in healthy controls (P < .001). Serum TG2 levels had positive correlations with each inflammatory mediator (P < .001). TG2 activity was increased in cord blood-derived human mast cells (CBMCs) and peripheral blood-derived human mast cells activated with IgE compared with those without activation (P < .05). CONCLUSION: Our findings suggest that TG2 expressed in and released from mast cells plays an important role in CSU pathogenesis.

Elevated Plasma Level of Interferon-λ1 in Chronic Spontaneous Urticaria: Upregulated Expression in CD8(+) and Epithelial Cells and Induction of Inflammatory Cell Accumulation.

Interferon- (IFN-) λ1 is regarded as a potent bio-active molecule in innate immunity. However, little is known about its role in chronic spontaneous urticaria (CSU). We therefore investigated expression of IFN-λ1 in CSU, its cellular location, and its influence on inflammatory cell accumulation by using flow cytometry analysis, skin tissue dispersion, immunohistochemical stain, and a mouse peritoneal inflammation model. The results showed that level of IFN-λ1 was 2.0-fold higher in plasma of the patients with CSU than the level in healthy control (HC) subjects. Among leukocytes examined, only CD8(+) T cells expressed more IFN-λ1 in CSU blood. Double labeling immunohistochemical staining revealed that IFN-λ1(+) inflammatory cells such as mast cells, eosinophils, B cells, neutrophils, and macrophages were mainly located in dermis, whereas epidermis tissue highly expressed IFN-λ1. IFN-λ1 induced a dose-dependent increase in number of eosinophils, lymphocytes, mast cells, macrophages, and neutrophils in the peritoneum of mice at 6 h following injection, which was inhibited by pretreatment of the animals with anti-intercellular adhesion molecule- (ICAM-) 1 and/or anti-L-selectin antibodies. In conclusion, IFN-λ1 is likely to play a role in the pathogenesis of CSU. Blocking IFN-λ1 production may help to reduce the accumulation of inflammatory cells in the involved CSU skin.