Anti-Anisakis antibodies in colon cancer patients and their relationship with γδ T-cells.

Many pathogens are related to carcinogenesis. Chronic inflammation, as a result of persistent infection, leads to DNA damage, higher expression of oncogenes, decreased apoptosis and immunosuppression, which are some of the reasons for cancer induction. Among parasites, Schistosoma, Opistorchis and Clonorchis are recognised as infectious agents which contribute to cancer. A relationship between Anisakis and cancer was hypothesised because cellular responses to Anisakis products could result in inflammation and DNA damage. Previous research has shown a decrease in CD8+ γδ T-cells and an increase in αß and γδ T-cell apoptosis in colon cancer (CC) samples. Ninety-two CC patients and 60 healthy subjects were recruited. γδ and αß T-cells were analysed, and their apoptosis was evaluated. Anti-Anisakis antibodies were tested in sera from CC patients and controls. Anti-Anisakis IgG, IgM, IgA and IgE antibodies were significantly higher in CC patients. A significant increase in anti-Anisakis IgA levels was observed in patients with angiolymphatic invasion. The number of all γδ T-cells, as well as CD3+ CD4+ αß T-cells, was significantly lower in CC patients. The apoptosis of all T-cells was significantly increased in patients with CC. We observed a significantly higher percentage of anti-Anisakis IgE positive patients having a deficit of CD3+ γδ T-cells. Our results suggest a relationship between Anisakis and CC.

Serum IgA contributes to the comprehension of Anisakis simplex associated chronic urticaria.

The phenotype of allergic diseases associated with Anisakis determines the pattern of cytokines related to antibody production. However, the role of serum IgA and the immunomodulatory mechanisms exerted by active infection of L3 or passive mucosal contact with A. simplex specific antigens has not been studied before. We measured serum cytokine by flow cytometry (IL-2, IL-4, IL-6, IL-10, TNF-α, IFN-γ, IL-17A, TGF-ß1) and antibody levels (IgE, IgG4, IgA) by ELISA against total and excretory-secretory (ES) antigens, Ani s 3,and the group of major allergens Ani s 1, Ani s 7, and Ani s 13 in sera from 10 patients with gastro-allergic anisakiasis (GAA), 11 Anisakis sensitization associated chronic urticaria (CU+) as well as 17 non-Anisakis-sensitized patients with chronic urticaria (CU-), compared with the urticaria control group (18 subjects). Specific IgE, IgG4 and IgA were high in the GAA, but IgA levels were significantly higher in the CU+ with respect the CONTROL group. We observed higher levels of the ratio IgA/IgG4 in CU+ than GAA group for Ani s 1, Ani s 7, Ani s 13 and ES. Furthermore, chronic urticaria (CU) patients showed significant lower levels of IL-10, IFN-γ and IL-17A than patients without CU. The anti-Ani s 13 IgA/IgG4 ratio correlated positively with pro-inflammatory cytokines and ratios (TNF-α, IL-17A, Th17/Th2, Type1/Type2 and TNF-α/IL-10) in CONTROL group. In general, Anti-Anisakis IgA/G4 ratio was high in CU patients. In conclusion, this study demonstrates the importance of serum IgA because it is associated with chronic urticaria independently of Anisakis sensitization.

A surgical case of inflammatory pseudotumor by hepatic anisakiasis.

Anisakiasis is a parasitic infection caused by the ingestion of raw or undercooked seafood infected with Anisakis larvae. It generally affects the gastrointestinal tract, particularly the stomach, but very rare cases have been reported in which infection of the liver leads to the formation of inflammatory pseudotumors. We herein report an extremely rare case of an inflammatory pseudotumor induced by hepatic anisakiasis that was laparoscopically resected for the purpose of both diagnosis and treatment. A 51-year-old woman underwent a routine medical checkup by ultrasound examination, which incidentally detected a 15-mm mass on the surface of S6 of the liver. Because a malignant tumor could not be ruled out on several preoperative imaging studies, laparoscopic partial resection of the liver was performed. Histopathological examination revealed Anisakis larva in the inflammatory pseudotumor, suggesting hepatic anisakiasis. This report describes an extremely rare case of an inflammatory pseudotumor induced by hepatic anisakiasis. Because the preoperative diagnosis could not be obtained by several imaging modalities, laparoscopic liver resection with a sufficient margin might be suitable for diagnosis and treatment of this disease.

A case of hepatic anisakidosis caused by Anisakis pegreffii mimicking liver cancer.

Extra-gastrointestinal anisakidosis is rare. We herein report an Anisakis pegreffii infection in a patient with hepatic anisakidosis diagnosed based on its molecular identification. A 71-year-old male patient had a hepatic tumor presenting as a low-density area of 20 mm in diameter in segment 6 of the liver on abdominal ultrasonography, computed tomography, and magnetic resonance imaging. The surgically resected pathological specimen revealed a necrotizing eosinophilic granuloma containing nematode larvae, possibly an Anisakis larva. Molecular and phylogenetic analysis demonstrated Anisakis larvae belonging to A. pegreffii. The present results will help identify and characterize unknown Anisakis species in histological sections.

A critical review of anisakidosis cases occurring globally.

A review was conducted to identify the most common causative agents of anisakidosis, the methods used for identification of the causative agents, and to summarize the sources of infection, and patients' demographics. A total of 762 cases (409 articles, inclusive of all languages) were found between 1965 and 2022. The age range was 7 months to 85 years old. Out of the 34 countries, Japan, Spain, and South Korea stood out with the highest number of published human cases of anisakidosis, respectively. This raises the question: Why are there few to no reports of anisakidosis cases in other countries, such as Indonesia and Vietnam, where seafood consumption is notably high? Other than the gastrointestinal tract, parasites were frequently found in internal organs such as liver, spleen, pancreas, lung, hiatal and epigastric hernia, and tonsils. There are also reports of the worm being excreted through the nose, rectum, and mouth. Symptoms included sore throat, tumor, bleeding, gastric/epigastric/abdominal/substernal/lower back/testicular pain, nausea, anorexia, vomiting, diarrhea, constipation, intestinal obstruction, intussusception, blood in feces, hematochezia, anemia, and respiratory arrest. These appeared either immediately or up to 2 months after consuming raw/undercooked seafood and lasting up to 10 years. Anisakidosis commonly mimicked symptoms of cancer, pancreatitis, type I/II Kounis syndrome, intussusception, Crohn's disease, ovarian cysts, intestinal endometriosis, epigastralgia, gastritis, gastroesophageal reflux disease, hernia, intestinal obstruction, peritonitis, and appendicitis. In these cases, it was only after surgery that it was found these symptoms/conditions were caused by anisakids. A range of not only mainly marine but also freshwater fish/shellfish were reported as source of infection. There were several reports of infection with >1 nematode (up to >200), more than one species of anisakids in the same patient, and the presence of L4/adult nematodes. The severity of symptoms did not relate to the number of parasites. The number of anisakidosis cases is grossly underestimated globally. Using erroneous taxonomic terms, assumptions, and identifying the parasite as Anisakis (based solely on the Y-shaped lateral cord in crossed section of the parasite) are still common. The Y-shaped lateral cord is not unique to Anisakis spp. Acquiring a history of ingesting raw/undercooked fish/seafood can be a clue to the diagnosis of the condition. This review emphasizes the following key points: insufficient awareness of fish parasites among medical professionals, seafood handlers, and policy makers; limited availability of effective diagnostic methodologies; and inadequate clinical information for optimizing the management of anisakidosis in numerous regions worldwide.

Anisakis spp, DNA detection in paraffin-embedded tissue biopsies recovered from patients with gastritis using real-time PCR in Bushehr, Persian Gulf, Iran.

Anisakiasis is a zoonotic fish-born parasitic disease caused by anisakid nematodes. Paraffin-embedded blocks containing biopsy samples taken from patients suffering gastritis with unknown causes were investigated by real-time PCR, in the Bushehr region, Iran; where human anisakiasis has not been reported, so far. A total of 50 paraffin-embedded blocks were randomly selected from 250 archived blocks of the patients with gastritis. A SYBER green-based real-time PCR targeting the ITS1 region was developed for the identification of Anisakis genus. An 86 bp partial fragment of the Anisakis spp. ITS1 gene was amplified successfully. A total of 3 out of 50 samples (6 %) had positive amplification in the samples and their pathology reports showed a significant finding of moderate chronic gastritis with or without ulcers. In conclusion, the developed qPCR could be used for detecting Anisakis spp. larval DNA in human biopsy blocks. This study showed the hidden human cases of anisakiasis in the Bushehr for the first time.

Primer reporte en Cuba de Anisakis spp. en muestras de pescado en conserva / First report in Cuba of Anisakis spp. in samples of canned fish

Introducción: Las especies de Anisakis representan uno de los grupos parasitarios patógenos transmitidos por alimentos más importantes en relación con sus capacidades zoonóticas y pueden producir una enfermedad emergente llamada anisakiosis. En Cuba, no existen reportes de la enfermedad como tampoco publicaciones sobre la detección del parásito en muestras de productos pesqueros. Objetivo: Identificar larvas de Anisakis spp. en muestras de productos pesqueros. Métodos: Se realizó un estudio para la búsqueda de larvas de Anisakis spp. en muestras de productos pesqueros en conserva recibidos en el Laboratorio de Parasitología de los alimentos del Instituto Nacional de Higiene, Epidemiología y Microbiología de Cuba. Se recibieron 96 muestras de dos marcas diferentes. A cada marca se le asignó las letras A o B para proteger la identidad del fabricante. Las larvas recuperadas fueron previamente aclaradas con lactofenol e identificadas morfológicamente por microscopía. Se utilizaron las claves de identificación para larvas de Anisakis spp. descritas en la literatura. Resultados: El 38,5 por ciento del total de muestras de pescado en conserva analizadas estuvieron parasitadas con larvas de Anisakis spp., con una frecuencia media de 1,2 larvas por cada submuestra. Las larvas fueron clasificadas de tercer estadio y de tipo I. Conclusiones: Por primera vez se identificó en Cuba larvas de Anisakis spp. en muestras de pescado en conserva y se proporcionó datos de interés a las autoridades sanitarias para el fortalecimiento de políticas públicas relacionadas con la calidad e inocuidad de los alimentos(AU)

Introduction: Anisakis species represent one of the most important foodborne pathogenic parasitic groups in relation to their zoonotic capabilities, and can produce an emerging disease called anisakiosis. In Cuba, there are no reports of the disease and there are no publications on the detection of the parasite in samples of fishery products. Objective: To identify Anisakis spp. larvae in samples of fishery products. Methods: A study was conducted to search for Anisakis spp. larvae in samples of canned fish products received at the Laboratory of Food Parasitology of the National Institute of Hygiene, Epidemiology and Microbiology of Cuba. Ninety-six samples of two different brands were received. Each brand was assigned letter A or B to protect the identity of the manufacturer. The larvae recovered were previously rinsed with lactophenol and identified morphologically by microscopy. The identification keys for Anisakis spp. larvae described in the literature were used. Results: 38.5 percent of the total canned fish samples analyzed were parasitized with Anisakis spp. larvae, with a mean frequency of 1.2 larvae per subsample. The larvae were classified as third instar and type I. Conclusions: For the first time in Cuba, Anisakis spp. larvae were identified in canned fish samples and provided data of interest to health authorities to strengthen public policies related to food quality and safety(AU)

Anisakiasis in Palatine Tonsil.

ABSTRACT: Anisakiasis is a parasitic infection caused by ingesting raw or undercooked fish and seafood infected with Anisakis larvae. Anisakis genus is mostly found in the mucosal or submucosal layer of the stomach and intestine. However, the reports of anisakiasis in tonsils are highly uncommon. A 54-year-old woman with clinical features of sore throat and foreign-body sensation for 10 days after eating raw and undercooked fish. A wriggling worm was noted beneath the mucosa of the right palatine tonsil upon endoscopic examination. The worm was immediately removed completely and histological examination revealed anisakiasis. Reports of anisakia-sis in the tonsils are scarce, but it should be considered at the initial physical examination of patients who visit the hospital for sore throat after eating raw fish. We report a case of anisakiasis in the palatine tonsils, which to date has been rarely reported in the literature.

Sliding Flap for the Wide Upper Eyelid Margin Defect After Cancer Removal.

BACKGROUND: Reconstruction of eyelid margin defects following resection of upper-eyelid skin malignancies is typically performed using a lower eyelid switch flap, including eyelash reconstruction. However, a subsequent procedure for flap separation, and prolonged swelling of the flap may occur as a complication. OBJECTIVE: The authors performed anterior lamellar reconstruction using a sliding flap with excess upper eyelid skin, a procedure that is a less invasive and simpler. MATERIALS AND METHODS: The authors performed anterior lamellar reconstruction using a sliding flap in 7 patients with full-thickness upper eyelid margin defect after skin cancer resection. The mean age of the patients was 76.0 years. The horizontal width of the defect in our cohort ranged from 11 to 25 mm and the vertical width ranged from 5 to 10 mm. RESULTS: All the flaps and mucosal grafts were well taken, and none of the patients complained of lack of eyelash reconstruction. However, eyelid margin irregularity, possibly due to flap or mucosal graft contraction, was observed in 2 patients, and 1 patient developed keratoconjunctivitis. CONCLUSIONS: The sliding flap technique is a minimally invasive and simple procedure for wide eyelid margin reconstruction. However, 2 patients developed eyelid margin irregularities and 1 patient developed keratoconjunctivitis. Those complications might have occurred owing to the condition of posterior lamellar reconstruction. Therefore, for the successful use of a sliding flap for anterior lamellar reconstruction, the form of the eyelid edge and the choice of posterior lamellar reconstruction are key considerations. In future, we plan to establish a better reconstructive technique by accumulating more evidence.

Anisakidosis diagnosticada tras la expulsión de vermes en deposiciones: forma poco frecuente de diagnóstico en humanos / Anisakidosis diagnosed after expulsion of worms in stools: a rare form of diagnosis in humans

Resumen La anisakidosis es una zoonosis parasitaria accidental y cosmopolita de los seres humanos, siendo su hospedero definitivo los mamíferos marinos como lobos de mar, focas y delfines, entre otros. El ser humano se infecta por el consumo en estado larvario del nemátodo de la familia Anisakidae presentes en pescados y mariscos crudos como la merluza o el congrio. Los helmintos se ubican preferentemente en el tubo digestivo alto, observándose la regurgitación del parásito a la boca o evidenciándose durante la realización de una endoscopía digestiva alta. En forma infrecuente las larvas pueden migrar al peritoneo o seguir su paso por el intestino delgado y colon, siendo inhabitual la expulsión por las deposiciones. Presentamos el caso de una expulsión dos larvas L3 de la familia Anisakidae en deposiciones.

Abstract Anisakidosis is an accidental and cosmopolitan parasitic zoonosis of human beings, its definitive host being marine mammals such as sea lions, seals and dolphins, among others. Humans are infested by consumption in the larval stage of the nematode of Anisakis present in raw fish and shellfish such as hake or conger eel. The infestation is preferably located in the upper digestive tract, observing the regurgitation of the parasite to the mouth or becoming evident during an upper gastrointestinal endoscopy. In rare cases, the larvae can migrate to the peritoneum or continue their passage through the small intestine and colon, with expulsion in stools being unusual. We present a case of expulsion of two larvae of the Anisakidae family in feces.

Immunohistopathological response against anisakid nematode larvae and a coccidian in Micromesistius poutassou from NE Atlantic waters.

A survey on Anisakis simplex (sensu stricto (s.s.)) from blue whiting, Micromesistius poutassou, in the north-eastern Atlantic Ocean revealed the occurrence of high infection levels of third larval stages in visceral organs and flesh. Larvae were genetically identified with a multilocus approach as A. simplex (s.s.). Histochemical, immunohistochemical and ultrastructural observations were conducted on 30 M. poutassou specimens. Gonads, pyloric caeca and flesh harboured encapsulated larvae of A. simplex (s.s.) but no intense host reaction was encountered around the parasite in the above organs. In the liver, the most infected organ, the larvae co-occurred with the coccidian Goussia sp. Within the granuloma around the A. simplex (s.s.) larvae, two concentric layers were recognized, an inner mostly comprising electron-dense epithelioid cells and an outer layer made of less electron-dense epithelioid cells. Macrophages and macrophage aggregates (MAs) were abundant out of the granulomas, scattered in parenchyma, and inside the MAs, the presence of engulfed Goussia sp. was frequent. In liver tissue co-infected with Goussia sp. and A. simplex (s.s.), hepatocytes showed cytoplasmic rarefaction and acute cell swelling. Results suggest that the host-induced encapsulation of A. simplex (s.s.) larvae is a strategic compromise to minimize collateral tissue damage around the larval infection sites, to facilitate the survival of both parasite and host.

The oil of garlic, Allium sativum L. (Amaryllidaceae), as a potential protectant against Anisakis spp. Type II (L3) (Nematoda) infection in Wistar rats.

The consumption of inadequately thermally treated fish is a public health risk due to the possible propagation of Anisakis larvae. The present study demonstrated the physiological and histopathological changes that accompanied an oral inoculation of crude extracts from fresh and thermally treated Anisakis Type II (L3) in rats. Worms were isolated from a marine fish and examined and identified using light and scanning electron microscopy. The study was performed in 6 rat groups: control (I), garlic oil (GO) inoculated (II), fresh L3 inoculated (III), thermally treated L3 inoculated (IV), fresh L3 + GO inoculated (V), and a thermally treated L3 + GO inoculated (VI) groups. Rats inoculated with fresh and thermally treated L3 showed abnormal liver and kidney functions associated with the destruction of normal architecture. GO produced a protective effect in rat groups inoculated with L3 extracts + GO via the amelioration of liver and kidney functions, which was confirmed by the marked normal structure on histology. Cooking of L3-infected fish induced severe alterations compared to uncooked fish. The administration of garlic before and after fish eating is recommended to avoid the dangerous effect of anisakids, even if they are cooked.

Expansion of T regulatory lymphocytes by murine bone marrow dendritic cells previously stimulated with Anisakis simplex larval antigens.

BACKGROUND: Anisakis simplex antigens present immunomodulatory properties by the induction of tolerogenic dendritic cells (DCs) in mice. OBJECTIVES: To study the capacity of DCs stimulated with A. simplex excretory-secretory (ES) or crude extract (CE) to generate Tregs. To investigate in vitro effects of antigens on the metabolic activity of splenocytes induced by LPS or CpG. METHODS: Phenotypic and functional characterization of T cells co-cultured with A. simplex-pulsed DCs was performed by flow cytometry. Lymphocyte mitochondrial respiratory activity was estimated by the Alamar Blue® Assay. FINDINGS: In C57BL/6J, CD4+CD25-Foxp3+ and CD8+CD25-Foxp3+ populations increased by CE-stimulated-DCs. In BALB/c, CE-stimulated-DCs caused the expansion of CD4+CD25+Foxp3+IL-10+ and CD8+CD25+Foxp3+IL-10+. IFN-γ expression raised in BALB/c CD4+CD25+ and CD4+CD25- for CE and ES, respectively. ES-stimulated-DCs increased CD4+CD25+ Foxp3+ and CD8+CD25- Foxp3+ expression in T cells. The association of ES or CE with LPS produced the increase in splenocyte activity in C57BL/6J. The association of CE with CpG decreased the proliferation caused by CpG in C57BL/6J. MAIN CONCLUSIONS: A. simplex increase the frequency of Tregs, which in turn produce IL-10 and IFN-γ. The host genetic base is essential in the development of anti-Anisakis immune responses (Th2, Th1, Treg).

Garlic oil as a fight against histological and oxidative stress abnormalities in Wistar rats after oral inoculation of Anisakis spp. Type II (L3) (Nematoda) / [O uso do óleo de alho na luta contra anormalidades histológicas e de estresse oxidativo em ratos Winstar após inoculação oral de Anisakis spp. Tipo II (L3) (Nematoda)]

The consumption of inadequately thermally treated fish is a public health risk due to the possible propagation of Anisakis larvae and their antigenic proteins, the causative agent of the zoonotic disease anisakidosis. The present study demonstrated the physiological and histopathological changes that accompanied an oral inoculation of crude extracts from fresh and thermally treated Anisakis Type II (L3) in Wistar albino rats. Nematode worms were isolated from the marine fish Dicentrarchus labrax. They were examined and taxonomically identified using light and scanning electron microscopy. The study was performed in 6 rat groups: a control group (I), a garlic oil (GO) inoculated group (II), a fresh L3 inoculated group (III), a thermally treated L3 inoculated group (IV), a fresh L3 + GO inoculated group (V), and a thermally treated L3 + GO inoculated group (VI). It was observed that rats inoculated with fresh and thermally treated L3 crude extracts showed abnormal oxidative stress markers associated with the destruction of normal architecture of spleen and thymus. GO produced a protective effect in rat groups inoculated with L3 extracts + GO administration via the amelioration of oxidative stress markers, which was confirmed by the marked normal structure of the organs' histology. Cooking of L3 infected fish induced severe physiological and histopathological alterations compared to uncooked infected fish. The administration of garlic before and after fish eating is recommended to avoid the dangerous effect of anisakids, even if they are cooked.(AU)

O consumo de peixes tratados termicamente de forma inadequada é um risco à saúde pública devido à possível propagação das larvas de Anisakis e suas proteínas antigênicas, o agente causador da doença zoonótica anisakidose. O presente estudo demonstrou as alterações fisiológicas e histopatológicas que acompanharam a inoculação oral de extratos brutos de Anisakis Tipo II (L3) frescos e termicamente tratados em ratos Wistar albinos. Vermes nematoides foram isolados do peixe marinho Dicentrarchus labrax e foram examinados e identificados taxonomicamente usando microscopia óptica e eletrônica de varredura. O estudo foi realizado em 6 grupos de ratos: grupo controle (I), grupo inoculado com óleo de alho (GO) (II), grupo inoculado com L3 fresco (III), grupo inoculado com L3 tratado termicamente (IV), grupo inoculado com L3 + GO fresco (V), e grupo inoculado com L3 + GO tratado termicamente (VI). Observou-se que ratos inoculados com extrato bruto L3 fresco e tratado termicamente mostraram marcadores de estresse oxidativo anormais associados à destruição da estrutura normal do baço e do timo. GO produziu um efeito protetor em grupos de ratos inoculados com extrato L3 + administração de GO através da melhoria dos marcadores de estresse oxidativo, que foi confirmada pela marcante estrutura normal da histologia dos órgãos. O cozimento de peixes infectados com L3 induziu alterações fisiológicas e histopatológicas graves quando comparado com peixes infectados não cozidos. Recomenda-se a administração de alho antes e depois da ingestão do peixe para evitar o efeito perigoso dos anisakídeos, mesmo se cozidos.(AU)

Intestinal obstruction caused by Anisakis.

A 77-year-old male presented to the Emergency Department due to a clinical and radiological pattern of intestinal obstruction. An abdominal computed tomography (CT) scan revealed a dilatation of the jejunum loops with a change in bowel caliber in the proximal ileum and segmental edema of the intestinal wall. An urgent laparotomy was performed which revealed adhesions between intestinal loops and an intraluminal mass in the proximal ileum with a change in the bowel caliber. The affected segment of the proximal ileum measuring 20 cm was resected and a small-bowel manual termino-terminal anastomosis was performed. The patient was discharged seven days following the surgery.

Expression and functionality of allergenic genes regulated by simulated gastric juice in Anisakis pegreffii.

To better understand the molecular mechanisms underlying allergens and parasite immunity and discover the stage-enriched gene expression of fish-borne zoonotic nematodes in the stomach, we used RNA-seq to study the transcriptome profiles of Anisakis pegreffii (Nematoda: Anisakidae, AP) in simulated gastric juice. Mobile L3 larvae were incubated in simulated medium at 37 °C in 5% CO2 (AP-GJ) and the control group larvae were collected in PBS under the same conditions (AP-PBS). We found that the sequences of A. pegreffii were highly similar to Toxocara canis sequences. Among the transcripts, there would be 138 up-regulated putative genes and 251 down-regulated putative genes in AP-GJ group. Several lipid binging-related genes were more highly expressed in AP-GJ larvae. Moreover, 17 allergen genes were up-regulated and 29 were down-regulated in AP-GJ larvae. Eleven allergen genes belonged to one or more of the following three categories: biological process, cellular component, and molecular function. According to KEGG analysis, the main pathways that were represented included protein processing in transcription, immune system, cancer, and infectious disease. In particular, the most significant changes in the expression of parasite-derived allergen products occurred in AP-GJ larvae. This study helps us to extend our understanding of the biology of the fish-borne zoonotic parasite A. pegreffii and could be helpful for more precise risk assessment and providing guidelines for allergic consumers.

Expansion of T regulatory lymphocytes by murine bone marrow dendritic cells previously stimulated with Anisakis simplex larval antigens

BACKGROUND Anisakis simplex antigens present immunomodulatory properties by the induction of tolerogenic dendritic cells (DCs) in mice. OBJECTIVES To study the capacity of DCs stimulated with A. simplex excretory-secretory (ES) or crude extract (CE) to generate Tregs. To investigate in vitro effects of antigens on the metabolic activity of splenocytes induced by LPS or CpG. METHODS Phenotypic and functional characterization of T cells co-cultured with A. simplex-pulsed DCs was performed by flow cytometry. Lymphocyte mitochondrial respiratory activity was estimated by the Alamar Blue® Assay. FINDINGS In C57BL/6J, CD4+CD25-Foxp3+ and CD8+CD25-Foxp3+ populations increased by CE-stimulated-DCs. In BALB/c, CE-stimulated-DCs caused the expansion of CD4+CD25+Foxp3+IL-10+ and CD8+CD25+Foxp3+IL-10+. IFN-γ expression raised in BALB/c CD4+CD25+ and CD4+CD25- for CE and ES, respectively. ES-stimulated-DCs increased CD4+CD25+ Foxp3+ and CD8+CD25- Foxp3+ expression in T cells. The association of ES or CE with LPS produced the increase in splenocyte activity in C57BL/6J. The association of CE with CpG decreased the proliferation caused by CpG in C57BL/6J. MAIN CONCLUSIONS A. simplex increase the frequency of Tregs, which in turn produce IL-10 and IFN-γ. The host genetic base is essential in the development of anti-Anisakis immune responses (Th2, Th1, Treg).