Mutations in SERPINB7, encoding a member of the serine protease inhibitor superfamily, cause Nagashima-type palmoplantar keratosis.

"Nagashima-type" palmoplantar keratosis (NPPK) is an autosomal recessive nonsyndromic diffuse palmoplantar keratosis characterized by well-demarcated diffuse hyperkeratosis with redness, expanding on to the dorsal surfaces of the palms and feet and the Achilles tendon area. Hyperkeratosis in NPPK is mild and nonprogressive, differentiating NPPK clinically from Mal de Meleda. We performed whole-exome and/or Sanger sequencing analyses of 13 unrelated NPPK individuals and identified biallelic putative loss-of-function mutations in SERPINB7, which encodes a cytoplasmic member of the serine protease inhibitor superfamily. We identified a major causative mutation of c.796C>T (p.Arg266(∗)) as a founder mutation in Japanese and Chinese populations. SERPINB7 was specifically present in the cytoplasm of the stratum granulosum and the stratum corneum (SC) of the epidermis. All of the identified mutants are predicted to cause premature termination upstream of the reactive site, which inhibits the proteases, suggesting a complete loss of the protease inhibitory activity of SERPINB7 in NPPK skin. On exposure of NPPK lesional skin to water, we observed a whitish spongy change in the SC, suggesting enhanced water permeation into the SC due to overactivation of proteases and a resultant loss of integrity of the SC structure. These findings provide an important framework for developing pathogenesis-based therapies for NPPK.

Transepidermal water loss measurement during infancy can predict the subsequent development of atopic dermatitis regardless of filaggrin mutations.

BACKGROUND: Atopic dermatitis (AD) is characterized by skin barrier dysfunction. Few studies have used noninvasive techniques to measure epidermis function in asymptomatic neonates. METHODS: Data of 116 infants from our previous randomized controlled study were analyzed. Skin barrier function was measured through transepidermal water loss (TEWL), stratum corneum hydration (SCH), and pH. The association between skin barrier function and time to AD development was evaluated. Patients were classified with high or low TEWL, and SCH and pH were assessed. The survival function of the time to AD development and hazard ratios were estimated. Allergic sensitization to egg white and ovomucoid at 32 weeks was assessed. RESULTS: Regardless of a filaggrin mutation, TEWL (optimal cutoff, 6.5 g/m(2)/h) of the forehead within the first week of life showed a lower p-value than TEWL of the leg, and the SCH and pH measurements. Baseline TEWL of the forehead was not different between groups, except for the mean gestational age, and it was not affected by humidity. We found a significant difference in the cumulative AD incidence between the high and low TEWL groups for the forehead only (p < 0.05). The probability without AD was lower in the high TEWL group than in the low TEWL group. For only the high TEWL group, AD development decreased significantly with daily emollient use. The high TEWL group exhibited a higher rate of sensitization to ovomucoid (p = 0.07). CONCLUSIONS: TEWL of the forehead during the first week of life is associated with AD development.

Application of moisturizer to neonates prevents development of atopic dermatitis.

BACKGROUND: Recent studies have suggested that epidermal barrier dysfunction contributes to the development of atopic dermatitis (AD) and other allergic diseases. OBJECTIVE: We performed a prospective, randomized controlled trial to investigate whether protecting the skin barrier with a moisturizer during the neonatal period prevents development of AD and allergic sensitization. METHODS: An emulsion-type moisturizer was applied daily during the first 32 weeks of life to 59 of 118 neonates at high risk for AD (based on having a parent or sibling with AD) who were enrolled in this study. The onset of AD (eczematous symptoms lasting >4 weeks) and eczema (lasting >2 weeks) was assessed by a dermatology specialist on the basis of the modified Hanifin and Rajka criteria. The primary outcome was the cumulative incidence of AD plus eczema (AD/eczema) at week 32 of life. A secondary outcome, allergic sensitization, was evaluated based on serum levels of allergen-specific IgE determined by using a high-sensitivity allergen microarray of diamond-like carbon-coated chips. RESULTS: Approximately 32% fewer neonates who received the moisturizer had AD/eczema by week 32 than control subjects (P = .012, log-rank test). We did not show a statistically significant effect of emollient on allergic sensitization based on the level of IgE antibody against egg white at 0.34 kUA/L CAP-FEIA equivalents. However, the sensitization rate was significantly higher in infants who had AD/eczema than in those who did not (odds ratio, 2.86; 95% CI, 1.22-6.73). CONCLUSION: Daily application of moisturizer during the first 32 weeks of life reduces the risk of AD/eczema in infants. Allergic sensitization during this time period is associated with the presence of eczematous skin but not with moisturizer use.

Distinct characteristics in Japanese dermatitis herpetiformis: a review of all 91 Japanese patients over the last 35 years.

We reviewed all 91 Japanese dermatitis herpetiformis (DH) patients reported over the last 35 years. The male-to-female ratio was 2 : 1. The mean age at onset was 43.8, and 13 years earlier for female patients. More than half of these Japanese DH patients showed granular IgA deposition in the papillary dermis, and another one-third showed fibrillar IgA deposition. The male patients with granular IgA deposition were 10 years older than those with fibrillar deposition. Whereas patients with granular IgA deposition showed typical distribution of the skin lesions, the predilection sites of DH tended to be spared in patients with fibrillar IgA deposition. Only 3 patients had definite gluten-sensitive enteropathy. There was a statistical difference in the frequency of human leukocyte antigen (HLA)-DR9 between the granular group and controls among Japanese. No patients had HLA-DQ2 or -DQ8, which is frequently found in Caucasian DH patients. The absence of HLA-DQ2/DQ8, the inability to identify celiac disease in most cases, the predominance of fibrillar IgA, and the unusual distribution of clinical lesions in Japanese patients suggest that Japanese DH may be a subset of DH patients and have a pathogenesis which is different from that currently proposed in Caucasian DH patients.

An epidemiological survey of anhidrotic/hypohidrotic ectodermal dysplasia in Japan: High prevalence of allergic diseases.

Anhidrotic/hypohidrotic ectodermal dysplasia (A/HED) is a congenital disorder characterized by anhidrosis/hypohidrosis and inadequate hair and dental dysplasia. Large-scale case studies of patients with A/HED have already been conducted overseas, while there has been no large-scale study, but only a few case reports in Japan. Furthermore, an epidemiological study of this disease has not been conducted in Japan to date. The purpose of this study was to investigate the clinical characteristics of A/HED patients, the status of genetic aberrations and complications of A/HED in Japan. Initially, we conducted a physician-initiated questionnaire survey of A/HED patients who visited medical institutions across Japan to investigate their backgrounds, clinical symptoms, genotypes, diagnostic methods and complications of A/HED. We also investigated the presence or absence of various allergic diseases (atopic dermatitis-like skin manifestations, bronchial asthma and food allergies). Questionnaires were also obtained from 26 patients with ectodermal dysplasia (ED) who visited four medical institutions. We compared the incidence of allergic diseases in healthy controls in a similar study to that of patients. Twenty-four of those patients were considered to have A/HED, of which 18 had a confirmed genetic diagnosis and were genotyped. All patients had anhidrosis or hypohidrosis, hair and dental dysplasia, and unique facial appearance; 23 patients had several cutaneous manifestations and seven patients had periorbital pigmentation. In addition, there was a significantly higher incidence of atopic dermatitis-like cutaneous manifestations, bronchial asthma and food allergies in the A/HED patients than in healthy controls. We report the results from a questionnaire survey of 24 patients with A/HED. This is the first report of a large number of A/HED patients in Japan. This study clarifies the status of clinical diagnosis and genetic testing of A/HED patients in Japan, as well as the characteristics of their skin symptoms and allergic complications.

Primary hypertrophic osteoarthropathy with severe arthralgia identified by gene mutation of SLCO2A1.

Male, 41 years old (yo) had been complaining of severe arthralgia. Past History indicated obstruction of intestinal tract at 12 yo and gastric ulcer at 13 yo. He had been suffered from polyarthralgia especially at PIP and MP joints of both hands from 38 yo. Finally, he complained severe arthralgia at PIP and MP joints with clubbed fingers without swelling. Biochemical finding indicated negative rheumatoid factor and anti-CCP antibody and normal MMP-3 level, but slightly increased CRP and ESR levels. Radiological finding indicated periostosis of　long bone without bone erosion and osteoporosis. His facial appearance was acromegalic with cutaneous manifestation of pachydermia and cutis vertices gyrate without abnormal growth hormone response. Histological findings of skin indicated oedema and hyperplasia of sebaceous glands with infiltration of lymphocytes around small blood vessels compatible with pachydermoperiostosis. In this case mutation of SLCO2A1 gene, which coded prostaglandin transport protein, was identified. The mutation c.940 + 1G > A of SLCO2A1 gene results in deletion of exon 7 and truncation of PG transporter (p.Arg288Glyfs*7). We suggest that severe arthralgia was originated from over production of prostaglandin E2. Further studies will be required.

Eicosanoid profiling in patients with complete form of pachydermoperiostosis carrying SLCO2A1 mutations.

Pachydermoperiostosis (PDP) is a genetic disease characterized by digital clubbing, periostosis, and pachydermia caused by mutated HPGD or SLCO2A1. Plasma prostaglandin (PG)E2 levels are increased in these patients. However, other eicosanoids have not been quantitated. We aimed to quantitate plasma eicosanoid levels in four patients carrying SLCO2A1 mutations by high-performance liquid chromatography-tandem mass spectrometry. PGE2 level was elevated in all patients; PGD2 and 11ß-PGF2 α levels were also increased in some patients, whereas eicosapentaenoic acid, docosahexaenoic acid, and arachidonic acid levels were decreased in all patients. Our data indicate a dysfunctional eicosanoid homeostasis and varied levels of PG in patients with a complete form of PDP carrying SLCO2A1 mutations. PGE2 levels seem to mostly affect the symptoms, with other eicosanoids possibly having a minor effect.

Safety and Efficacy of the Sirolimus Gel for TSC Patients With Facial Skin Lesions in a Long-Term, Open-Label, Extension, Uncontrolled Clinical Trial.

INTRODUCTION: Our previous clinical studies have demonstrated the short-term efficacy and safety of the sirolimus gel for patients with tuberous sclerosis complex (TSC). However, long-term clinical evidence is lacking. Our objective was to assess the safety and efficacy of long-term treatment with the sirolimus gel for the skin lesions of TSC patients. METHODS: We conducted a multicenter, open-label, uncontrolled clinical trial in 94 Japanese patients with TSC. Patients applied the 0.2% sirolimus gel on their face or head twice daily for > 52 weeks (maximum 136 weeks for safety). The safety endpoints were the rate of adverse event (AE)-caused discontinuation (primary endpoint) and the incidence of AEs. The efficacy endpoint was the response rate of angiofibromas, cephalic plaques, and hypomelanotic macules. RESULTS: Among 94 enrolled patients (mean age, 21 years; range 3-53 years), the rate of AE-caused discontinuation was 2.1% (2/94 patients). Although application site irritation and dry skin occurred relatively frequently, none of the drug-related AEs were serious; most of the drug-related AEs resolved rapidly. The major drug-related AEs (≥ 5% in incidence) were application site irritation (30.9%), dry skin (27.7%), acne (20.2%), eye irritation (8.5%), pruritus (8.5%), erythema (7.4%), dermatitis acneiform (6.4%), and dermatitis contact (5.3%). The response rates of angiofibromas, cephalic plaques, and hypomelanotic macules were 78.2% [95% confidence interval (CI) 68.0-86.3%], 66.7% (95% CI 51.1-80.0%), and 72.2% (95% CI 46.5-90.3%), respectively. CONCLUSIONS: The gel was well tolerated for a long time by patients with TSC involving facial skin lesions and continued to be effective. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT02634931.

Adjuvant effect of lipopolysaccharide on the induction of contact hypersensitivity to haptens in mice.

BACKGROUND: Toll-like receptor (TLR) 4 is a critical receptor and signal transducer for lipopolysaccharide (LPS), a major component of Gram-negative bacteria. The MyD88-independent pathway downstream of TLR4 leads to functional dendritic cell (DC) maturation, although LPS-induced cytokine production from DCs is MyD88-dependent. OBJECTIVES: We investigated whether intracutaneously injected LPS alters the functions of cutaneous DCs, leading to enhanced contact hypersensitivity (CH). METHODS: The ear swelling response was measured to evaluate the magnitude of CH. Cell proliferation of allogeneic splenocytes stimulated by DC-enriched draining lymph node (LN) cells was measured by performing a [(3)H]-thymidine incorporation assay. Epidermal I-A+ cells were evaluated under an epifluorescent microscope. I-A+ FITC-bearing cells from the draining LNs 24h after FITC application were analyzed on FACScan. RESULTS: LPS augmented CH induction in C3H/HeN (HeN) and MyD88-knockout (KO) mice but not in C3H/HeJ (HeJ) and H-2S(d)-bearing strains such as BALB/c mice. LPS failed to augment the allo-stimulatory ability of DCs in the draining LNs after hapten applications. LPS altered the density and morphology of epidermal I-A+ cell in HeN and BALB/c mice but not in TLR4-deficient HeJ mice. LPS increased the proportion of I-A+ FITC-bearing cells in the LNs 24h after FITC application in HeN, but not in BALB/c and HeJ. CONCLUSIONS: LPS augments the ability of DCs to migrate to the draining LNs, leading to enhanced CH via a TLR4-dependent, MyD88-independent pathway. The different effects of LPS on CH in some strains of mice may explain individual differences in the susceptibility to establish CH to daily antigen exposures in clinical settings.

Regulatory effects of antihistamines on the responses to staphylococcal enterotoxin B of human monocyte-derived dendritic cells and CD4+ T cells.

BACKGROUND: Antihistamines are widely used for the treatment of allergic diseases, such as urticaria and allergic rhinitis. They are also effective for the treatment of diseases in which T cells are mainly involved in the pathogenesis, such as atopic dermatitis (AD) and contact dermatitis. Dendritic cells (DCs) drive polarization of naive T cells into Th1 or Th2 subsets, and are also likely to be involved in AD pathogenesis. OBJECTIVES: The aim of this study was to determine the effects of antihistamines on DCs and CD4+ T cells. METHODS: Human monocyte-derived DCs (MoDCs) and autologous CD4+ T cells were obtained from healthy subjects, and cultured together or independently in the presence of antihistamines. As a stimulant, we used staphylococcal enterotoxin B or the combination of anti-CD3 monoclonal antibody (mAb) and anti-CD28 mAb. The concentrations of cytokines and chemokines in culture supernatants were measured by ELISA. The expression of surface molecules on MoDCs was measured by flow cytometry. Cell proliferation in the cocultures of MoDCs and CD4+ T cells (DC-T cocultures) was measured by a [(3)H] thymidine incorporation assay. RESULTS: Antihistamines inhibited the production of IFN-gamma, and enhanced the production of IL-4 in DC-T cocultures. Antihistamines inhibited the production of TNF-alpha, TARC, MDC, IP-10, and Mig from MoDCs. Epinastine, one of antihistamines, suppressed the expression of ICAM-1 (CD54) on MoDCs. Epinastine also inhibited the proliferation of CD4+ T cells cocultured with MoDCs. CONCLUSIONS: Our findings show that antihistamines regulate immune responses by affecting the interaction between DCs and CD4+ T cells, and further DCs and CD4+ T cells independently, which may partially contribute to the control of allergic diseases such as AD and contact dermatitis.

Relationship among human herpesvirus 6 reactivation, serum interleukin 10 levels, and rash/graft-versus-host disease after allogeneic stem cell transplantation.

BACKGROUND: The relationship between herpesvirus reactivation and graft-versus-host disease (GVHD) after allogeneic stem cell transplantation (allo-SCT) is unclear. OBJECTIVE: We sought to examine the relationship between human herpesvirus (HHV) reactivation and rash/GVHD after allo-SCT by prospective evaluation. METHODS: Fifteen patients who had received allo-SCT underwent prospective serial examinations for human herpesvirus 6 (HHV-6), HHV-7, cytomegalovirus, and Epstein-Barr virus DNA in the blood by polymerase chain reaction and real-time polymerase chain reaction. Serum interferon gamma, interleukins 4 and 10, tumor necrosis factor alpha, and soluble interleukin 2 receptor (sIL-2R) were also measured. RESULTS: In 10 of 15 patients, macular/papular eruptions were seen after allo-SCT and GVHD was diagnosed. In 8 patients with rash, HHV-6 DNA levels correlated with the cutaneous manifestation. Interleukin 10 and sIL-2R also increased in association with rash. LIMITATIONS: The number of patients in our study was relatively small. Not all patients were examined for cytokines and sIL-2R. CONCLUSIONS: HHV-6 reactivation may be involved in the pathogenesis of rash/GVHD after allo-SCT.

Effectiveness of non-steroidal anti-inflammatory drugs among patients with primary hypertrophic osteoarthropathy: A systematic review.

BACKGROUND: Primary hypertrophic osteoarthropathy (PHO), also known as pachydermoperiostosis is a rare genetic disease which predominantly affects skin, bone and soft connective tissue. It is characterized by the triad of pachydermia, digital clubbing and periostosis of long bones. Arthralgia or arthritis is also present in most of the cases. Genetic studies have identified the impaired PGE2 metabolism as a culprit for hypertrophic osteoarthropathy in PHO cases. We conducted a systematic review to examine the effectiveness of Non-Steroidal Anti-Inflammatory Drugs (NSAIDs), a PGE2 synthesis blocker to reduce the symptoms among PHO patients. METHODS: We searched the evidence in five databases; Cochrane Library, CINAHL, EMBASE, MEDLINE, and PubMed. We reported the evidence using narrative synthesis. RESULTS: Out of 238 identified studies, we selected 26 for the synthesis. All were case reports which included a total of 54 patients. Among them, 39 patients were treated with at least one type of NSAIDs. Around 70% of the patients treated with NSAIDs had clinical improvement for their symptoms, mostly arthritis or arthralgia symptoms. CONCLUSION: NSAIDs were effective in improving arthralgia or arthritis symptoms in majority of the PHO patients. Therefore, we recommend the use of NSAIDs in PHO patients to treat arthralgia or arthritis.

A male Korean who was diagnosed with chronic enteropathy associated with SLCO2A1 (CEAS): case report with literature review.

OBJECTIVE: To further disseminate the nomenclature of chronic enteropathy associated with SLCO2A1 (CEAS), especially for physicians in China and Korea where the genetic feature of SLCO2A1 gene mutations related hypertrophic osteoarthropathy and pachydermia had been extensively studied. SLCO2A1 gene mutations related hypertrophic osteoarthropathy and pachydermia had been extensively studied. DESIGN: A case report with literature review of SLCO2A1 gene mutations-related disorders. RESULTS: A 38-year-old Korean presented to a tertiary hospital with dizziness, abdominal pain and melena. He had a positive faecal occult blood test on initial workup. Oesophagogastroduodenal endoscopy (OGD), colonoscopy and CT scan were unremarkable and showed no obvious cause for his melena. Capsule endoscope and roentgen barium studies were performed, revealing an erythematous mucosa with ulcers in the jejunum and stenosis to the jejunal-ileal junction. Next-generation sequencing was then performed and discovered point mutations of SLCO2A1 gene's seven exon (940+1 G>A) and 13 exon (1807 C>T) allele. This Korean patient with CEAS is the first documented case noted outside of the Japanese population. CONCLUSION: CEAS is not uniquely found in Japanese individuals. There are lots of similarities between CEAS and primary hypertrophic osteoarthropathy, the two entity may just be the two sides of one same coin. International and multidisciplined efforts are required to further study this complicated disorder.

Sirolimus Gel Treatment vs Placebo for Facial Angiofibromas in Patients With Tuberous Sclerosis Complex: A Randomized Clinical Trial.

Importance: Most patients with tuberous sclerosis complex (TSC), an autosomal-dominant disorder that is caused by the constitutive activation of mammalian target of rapamycin, experience disfigurement caused by skin lesions involving facial angiofibromas. Many have been left untreated because of a lack of therapeutic options that are less invasive than surgery or laser treatment. Objective: To confirm the efficacy and safety of sirolimus gel, 0.2%, for treatment of patients with angiofibromas and/or skin lesions. Design, Setting, and Patients: Multicenter, randomized clinical trial at 9 centers in Japan from December 2015 to October 2016 including 62 children and adults with TSC. Interventions: Patients who developed angiofibromas were randomly assigned, in a 1:1 ratio, to receive sirolimus gel, 0.2%, or placebo, each applied topically twice daily for 12 weeks. Main Outcomes and Measures: The primary end point was composite improvement in the size and color of angiofibromas in photographs at week 12 of treatment. It was assessed by an independent review committee comprising 3 blinded dermatologists who categorized patient results into the following 6 categories: "markedly improved," "improved," "slightly improved," "unchanged," "slightly aggravated," and "aggravated." Results: Sixty-two patients (27 pediatric and 35 adult; 34 [55%] female; mean [SD] age, 22.5 [11.9] years) were enrolled and randomly assigned to receive sirolimus gel, 0.2% (30 patients), or placebo (32 patients). The response rates of angiofibromas at weeks 4, 8, and 12 of treatment were 0 each in the placebo group in contrast to 20% (95% CI, 8%-39%; P = .01), 43% (95% CI, 26%-63%; P < .001), and 60% (95% CI, 41%-77%; P < .001), respectively, in the sirolimus group. None of the 31 assessable patients in the placebo group were rated improved or better, and 26 of them (84%) were rated unchanged. In contrast, 5 (17%) and 13 (43%) patients in the sirolimus group were rated markedly improved and improved, respectively. Adverse events were mild to moderate and were observed in 27 (90%) and 22 (69%) patients in the sirolimus and placebo groups, respectively; however, none of the trial participants discontinued treatment. Acute pancreatitis developed as a serious adverse event in 1 patient in the sirolimus group, and the patient recovered soon after hospitalization without discontinuing treatment. Conclusions and Relevance: Sirolimus gel, 0.2%, demonstrated a significant clinical benefit for patients with TSC involving angiofibromas, thus providing a promising therapeutic modality. Trial Registration: ClinicalTrials.gov Identifier: NCT02635789.

Paraneoplastic pemphigus presenting as erythrodermic lichenoid dermatitis with concomitant features of pemphigus foliaceus.

We describe a patient with paraneoplastic pemphigus who presented with erythrodermic lichenoid dermatitis, later developing blisters of pemphigus foliaceus type and oral erosive lesions. In addition to antibodies against the plakin family proteins, the patient's serum was positive for anti-desmoglein 1 antibodies without coexisting anti-desmoglein 3 activities by enzyme-linked immunosorbent assay, which is a very rare autoantibody profile in paraneoplastic pemphigus.

Compound heterozygous mutations including a de novo missense mutation in ABCA12 led to a case of harlequin ichthyosis with moderate clinical severity.

Harlequin ichthyosis (HI) is one of the most devastating genodermatoses. Recently, ABCA12 mutations were identified as the cause of HI. A newborn Japanese male demonstrated the typical features of HI. The patient was treated with oral etretinate and his general condition has been good (now aged 1.5 years). This patient with moderate clinical severity was compound heterozygous for a novel de novo missense mutation 1160G > A (S387N) in exon 10 and a maternal deletion mutation 4158_4160delTAC (T1387del) in exon 28 of ABCA12. T1387del was a deletion of a highly conserved threonine residue within the first adenosine 5' triphosphate-binding domain and is thought to seriously affect the function of the ABCA12 protein. Conversely, the residue 387 is located outside the known active sites of ABCA12 and S387N is predicted not to lead to a serious functional deficiency in ABCA12. Electron microscopy revealed abnormal lamellar granules in the granular layer cells and a moderate number of lipid vacuoles in the cornified cells. Disturbed glucosylceramide transport was confirmed in the cultured keratinocytes from the patient. No de novo mutation in ABCA12 has yet been reported either in HI or lamellar ichthyosis. The present case suggested that a de novo ABCA12 mutation might underlie HI.

Mosquito salivary gland extracts induce EBV-infected NK cell oncogenesis via CD4 T cells in patients with hypersensitivity to mosquito bites.

Severe hypersensitivity to mosquito bites (HMB) is characterized by intense local skin reactions and systemic symptoms such as high fever, lymphadenopathy, and hepatosplenomegaly. Patients with HMB often have natural killer (NK) cell lymphocytosis associated with Epstein-Barr virus (EBV) infection. Here we investigated whether mosquito bites have any influence on the oncogenesis of EBV-infected NK cells. We examined six HMB patients with EBV-infected NK cell lymphocytosis. We first demonstrated that CD4+ T cells, but not NK cells, proliferated well in response to mosquito salivary gland extracts (SGE), especially to SGE of Aedes albopictus. When NK cells were cocultured with autologous CD4+ T cells stimulated by mosquito SGE, the expression of viral oncogene latent membrane protein 1 (LMP1) was remarkably enhanced. Next, we stimulated mononuclear cells of the patients with mosquito SGE, and NK cell counts were monitored for 28 d. The counts changed little from initial levels in the culture with mosquito SGE, whereas they decreased steadily in the culture without the extracts. Furthermore, we detected LMP1 mRNA in the skin lesion induced by mosquito SGE. These results suggest that mosquito bites can induce expression of the viral oncogene LMP1 in NK cells via mosquito antigen-specific CD4+ T cells, which is involved in the oncogenesis of NK cells in vivo.