Antibodies to age-ß2 glycoprotein I in patients with anti-phospholipid antibody syndrome.

Anti-phospholipid antibody syndrome (APS) is a systemic autoimmune disease characterized clinically by arterial and/or venous thromboses, recurrent abortions or fetal loss and serologically by the presence of 'anti-phospholipid antibodies' (aPL). The main target antigen of the antibodies is ß2 glycoprotein I (ß2 GPI). Post-translational oxidative modifications of the protein have been widely described. In this study we aimed to analyse sera reactivity to glucose-modified ß2 GPI (G-ß2 GPI). Sera collected from 43 patients with APS [15 primary APS (PAPS) and 28 APS associated with systemic lupus erythematosus (SLE) (SAPS)], 30 with SLE, 30 with rheumatoid arthritis (RA) and 40 healthy subjects were analysed by an enzyme-linked immunosorbent assay (ELISA) using a G-ß2 GPI. Nine of 15 consecutive PAPS out-patients (60%) and 16 of 28 SAPS (57.1%) showed serum antibodies [immunoglobulin (Ig)G class] against G-ß2 GPI (anti-G-ß2 GPI) by ELISA. The occurrence of anti-G-ß2 GPI was significantly higher in APS patients compared to patients suffering from SLE. No RA patients or control healthy subjects resulted positive for anti-G-ß2 GPI. Of note, aG-ß2 GPI prompted to identify some APS patients (four PAPS and seven SAPS), who were negative in the classical anti-ß2 GPI test. Moreover, in APS patients, anti-G-ß2 GPI titre was associated significantly with venous thrombosis and seizure in APS patients. This study demonstrates that G-ß2 GPI is a target antigen of humoral immune response in patients with APS, suggesting that ß2 GPI glycation products may contain additional epitopes for anti-ß2 GPI reactivity. Searching for these antibodies may be useful for evaluating the risk of clinical manifestations.

Plaque-infiltrating T lymphocytes in patients with carotid atherosclerosis: an insight into the cellular mechanisms associated to plaque destabilization.

AIM: Inflammation plays a crucial role in the progression of atherosclerotic plaques. The aim of the present study was to investigate phenotypic and functional characteristics of plaque-infiltrating T lymphocytes associated with a complicated phenotype of carotid atherosclerotic lesions. METHODS: Atherosclerotic plaques were obtained from 17 patients undergoing carotid endarterectomy and cultured to isolate infiltrating T lymphocytes. Blood samples were obtained from patients and from 20 sex- and age-matched healthy subjects. The presence of lymphocytes (CD3+ cells) within atherosclerotic plaques was determined by immunohistochemistry. Phenotypic characteristics and intracellular cytokine expression of plaque-infiltrating and circulating T lymphocytes were determined by flow cytometry. Cytokine levels in supernatants from infiltrating T cell cultures were evaluated by enzyme-linked immunosorbent assay. RESULTS: A higher number of CD3+ cells was detected in complicated than in uncomplicated plaques. Complicated plaques had higher percentages of tumor necrosis factor (TNF)-α- and interferon (IFN)-γ- positive cells than uncomplicated ones, especially in CD4+ subpopulation. In patients the percentages of TNF-α-positive cells were higher in infiltrating than in circulating lymphocyte samples. Intracellular TNF-α, IFN-γ, interleukin (IL)-4 and IL-10 expression resulted higher in circulating lymphocyte samples from patients than in those from healthy subjects. Supernatants of infiltrating T cell cultures from complicated plaques showed higher levels of TNF-α and lower levels of IL-4 than those from uncomplicated plaques. CONCLUSION: Our data provide new information on the presence of increased percentages of pro-inflammatory T lymphocytes in complicated plaques with respect to uncomplicated ones and support the concept of the key role played by activated T cells in the progression of atherosclerotic lesions.

Oxidized human beta2-glycoprotein I: its impact on innate immune cells.

Beta2-glycoprotein I (ß2-GPI), an abundant 50 kDa plasma glycoprotein, is the most common target for antiphospholipid antibodies (aPLs). These autoantibodies are associated with thrombotic events in patients with anti-phospholipid antibody syndrome (APS) and systemic lupus erythematosus (SLE) and are proatherogenic. ß2-GPI can also stimulate a vigorous adaptive cellular immune response in these patients. Although much is known about ß2-GPI as a cofactor in autoimmune diseases, crucial information is still lacking to clarify why this abundant self plasma protein is the target of autoimmune responses. Throughout the years, a remarkable number of theories have been proposed to explain how the immune system recognises self. On the basis of a large variety of epidemiological, clinical and experimental evidence, it has been suggested that an unfortunate interplay of genetic susceptibility and environmental factors may play an important role in generating an abnormal immune response. Among the environmental factors, oxidative stress is one of the major events causing protein structural modifications, thus inducing the appearance of neo/cryptic epitopes of ß2-GPI able to activate the immune system. In particular, oxidized ß2-GPI is able to induce phenotypic and functional maturation of dendritic cells which represent the link between innate and adaptive immunity. Chronic activation of autoimmune reactions against this self protein modified by oxidative events may contribute to local and systemic inflammation, thus sustaining endothelial dysfunction in patients with APS, SLE and cardiovascular diseases. The role of oxidative stress in ß2-GPI-mediated immune response is described in the light of our research experience and of relevant literature emerging in the field.

Identification of IP-10 and IL-5 as proteins differentially expressed in human complicated and uncomplicated carotid atherosclerotic plaques.

Inflammation plays a crucial role in the development and progression of atherosclerotic plaques. The aim of this study is to compare culture supernatants from uncomplicated and complicated carotid atherosclerotic plaques by a multiplex approach, to assess the molecular mediators associated with a plaque complicated phenotype. Atherosclerotic plaques were obtained from 17 patients undergoing carotid endarterectomy. Supernatants from plaque cultures were evaluated by Bio-Plex cytokine assay to determine 27 pro- and anti-inflammatory cytokines, chemokines and growth factors. Complicated plaques secreted higher levels of IP-10 (p = 0.027) and lower levels of IL-5 (p = 0.045) than did uncomplicated ones. Distinctive secretory patterns of cytokines, chemokines and growth factors were present in the two types of plaque. Our study identifies IP-10 and IL-5 as proteins differentiating complicated and uncomplicated plaques from human carotid arteries and provides new insights into the interplay of molecular mediators with atherosclerotic plaque progression.

Beta2-glycoprotein I is a target of T cell reactivity in patients with advanced carotid atherosclerotic plaques.

Evidence in animal models that beta2-glycoprotein I (beta2GPI), the principal target of autoimmune antiphospholipid antibodies, is involved in the initiation and progression of atherosclerosis, prompted us to investigate the possible role of this self protein as a target autoantigen of immune reactions in patients with carotid atherosclerosis. Plaque-infiltrating T lymphocytes from patients, and circulating T lymphocytes from patients and healthy subjects were tested by cell proliferation assay and by flow cytometry for intracellular cytokine expression in response to beta2GPI. ELISA was used to detect cytokine production in culture supernatants and anti-beta2GPI/anti-cardiolipin antibodies in serum samples. Eight of 35 PBMC samples and 1 of 5 plaque-infiltrating T lymphocyte samples from patients proliferated in response to beta2GPI, whereas PBMC from healthy subjects did not. Patients PBMC samples that proliferated in response to beta2GPI produced significantly higher IFN-gamma and TNF-alpha than non-proliferating PBMC. beta2GPI-specific plaque-derived T lymphocytes expressed IFN-gamma, TNF-alpha and IL-4, suggesting concomitant Th1 and Th2 activation. Only one patients serum was positive for anti-beta2GPI and anti-cardiolipin IgM antibodies. These new findings indicate that beta2GPI induces a cellular immune response in a subpopulation of patients with carotid atherosclerosis thus contributing to the inflammatory responses involved in carotid atherosclerotic disease.

Association of intracellular pro- and anti-inflammatory cytokines in peripheral blood with the clinical or ultrasound indications for carotid endarterectomy in patients with carotid atherosclerosis.

Early non-invasive diagnostic information would be useful in identifying patients at risk of progressive carotid atherosclerosis, despite an apparently harmless plaque on ultrasound imaging. In this study, we assessed the possible association of intracellular cytokines in peripheral blood with the ultrasound (stenosis > or = 70%) and clinical indications (transient ischaemic attack, amaurosis fugax or stroke) for carotid endarterectomy (CEA) in patients. Intracellular cytokine expression was determined in 106 patients (67 undergoing and 39 not undergoing CEA). Cells primed for the proinflammatory cytokines tumour necrosis factor (TNF)-alpha, interferon (IFN)-gamma, interleukin (IL)-1beta, IL-6, IL-8 and the anti-inflammatory cytokines IL-4 and IL-10 were found in significantly higher percentages in patients undergoing CEA than in patients who were not (P < 0.05). Intracellular cytokine expression was significantly higher in patients undergoing CEA who had stenosis > or = 70% (TNF-alpha, IFN-gamma, IL-1beta, IL-6, IL-4 and IL-10), with previous stroke (IFN-gamma, IL-1beta, IL-6, IL-8, IL-4 and IL-10) and with amaurosis fugax (IFN-gamma, IL-6, IL-4 and IL-10) than in patients not undergoing CEA. Increased intracellular cytokines in patients' peripheral blood might be a warning signal indicating progressive atherosclerosis. If so, intracellular cytokine monitoring could help in selecting patients at high risk of future clinical cardiovascular events and therefore most likely to benefit from CEA or adjustment of pharmacological therapy.

Chronic and acute alcohol exposure prevents monocyte-derived dendritic cells from differentiating and maturing.

Increasing evidence suggests that alcohol abuse may be linked to adverse immunomodulatory effects on immune responses. Our study was undertaken to clarify the immunological consequences of chronic and acute alcohol exposure on differentiation and maturation of human dendritic cells (DCs). Using immunochemical and cytofluorimetric analysis we determined the phenotype and functions of monocyte-derived DCs from alcoholics and healthy subjects and analyzed their ability to respond to lipopolysaccharide (LPS) in the presence or absence of ethanol (EtOH) exposure. Our results showed that alcoholics inverted exclamation mark| monocytes differentiated to immature DCs with altered phenotype and functions (alc-iDCs). Alc-iDCs showed fewer CD1a+ cells, weaker CD86 expression and higher HLA-DR expression associated with lower endocytosis and allostimulatory functions than iDCs from healthy subjects (control-iDCs). Despite these impairments, alc-iDCs produced TNF-alpha and IL-6 in large amounts. LPS stimulation failed to induce full phenotypical and functional alc-iDC maturation. In vitro acute EtOH exposure also prevented alc-iDCs and control-iDCs from maturing in response to LPS. T-cell priming experiments showed that EtOH treatment prevented LPS-stimulated control-iDCs from priming and polarizing naïve allogeneic T cells into Th1 cells, thus favouring a predominant Th2 environment. Collectively, our results provide evidence that chronic and acute alcohol exposure prevents DCs from differentiating and maturing in response to a microbial stimulus.

Screening of an Echinococcus granulosus cDNA library with IgG4 from patients with cystic echinococcosis identifies a new tegumental protein involved in the immune escape.

The worldwide problem of chronic Echinococcus granulosus disease calls for new parasite-derived immunomodulatory molecules. By screening an E. granulosus cDNA library with IgG4 from patients with active cystic echinococcosis, we identified a cDNA that encodes a predicted partial protein that immunofluorescence studies localized in the protoscolex tegument and on the germinal layer of cyst wall. We named this protein EgTeg because the 105 amino acid sequence scored highest against a family of Schistosoma tegumental proteins. Evaluating the role of EgTeg in the human early inflammatory response we found that EgTeg significantly inhibited polymorphonuclear cell (PMN) chemotaxis. Cytometric analysis of intracellular cytokines disclosed a significantly higher percentage of cells producing IL-4 than IFN-gamma (P = 0.001, Student's t-test) in T lymphocytes from patients with cystic echinococcosis stimulated with EgTeg. EgTeg induced weak Th1-dependent proliferation in 42% of patients' peripheral blood mononuclear cells. In immunoblotting (IB) analysis of total IgG and IgG subclass responses to EgTeg in patients with cystic echinococcosis, patients with other parasitoses, patients with cystic lesions and healthy controls, total IgG specific to EgTeg yielded high sensitivity (73%) but low specificity (44%) precluding its use in immunodiagnosis. Conversely, IgG4 specific to EgTeg gave acceptable sensitivity (65%) and high specificity (89%) suggesting its use in immunodiagnosis to confirm ultrasound documented cysts suggestive of E. granulosus. Because the new tegumental antigen EgTeg inhibits chemotaxis, induces IL-4-positive T lymphocytes and noncomplement fixing antibodies (IgG4) it is an immunomodulatory molecule associated with chronic infection.

Morphological analysis of cell subpopulations within carotid atherosclerotic plaques.

Atherosclerosis is considered a chronic inflammatory process, prompted by lipid accumulation and propagated by cell-mediated mechanisms. The present work was undertaken to clarify this process by characterizing cellular components of inflammatory infiltrate localized within atheroma. Cryostat sections of atherosclerotic lesions obtained from human carotid endarterectomy were analysed immunohistochemically by using monoclonal and polyclonal antibody directed against T cell subpopulations (CD3, CD4, CD8), B cells (CD20), plasma cells (CD138), macrophages (CD14), mast cells (anti-tryptase). Our results assess that T cells are the predominant cell type among plaque infiltrating inflammatory cells. B cells were detected near the lipid core of atheroma and clusters of plasma cells were observed within cellular infiltrates in most plaques. Numerous tryptase positive mast cells were noticed in many areas of complicated lesions. Our results indicate the presence of many inflammatory cells within type V and VI atherosclerotic plaques, suggesting the involvement of those cells in plaque progression. In fact it was previously shown that stability of atherosclerotic lesions is influenced by mast cell-released matrix metalloproteinases which induce plaque rupture and by cytokines and chemokines which increase local inflammatory response and are produced by lymphocytes and macrophages.

Screening of a HUAEC cDNA library identifies actin as a candidate autoantigen associated with carotid atherosclerosis.

The humoral immune response to endothelium has a pivotal role in the development of atherosclerosis. Using a molecular method, we sought to identify endothelial autoantigens in carotid atherosclerosis. Immunoscreening of a HUAEC expression library with IgG from a pool of two sera from patients with carotid atherosclerosis identified a clone specific to actin. We evaluated actin-specific IgG reactivity in patients with carotid atherosclerosis and compared responses with those in patients with systemic lupus erythematosus and type 1 diabetes mellitus and in healthy subjects. Enzyme-linked immunoassay detected actin-specific IgG in a significantly higher percentage of sera from patients with atherosclerosis and systemic lupus erythematosus than from healthy subjects (16/61, 26% and 13/33, 39%versus 2/41, 5%, P = 0.012 and P < 10(-4), by chi2 test). Mean optical density values were significantly higher in patients than in healthy subjects (P < 10(-4) by Student's t-test). Patients with atherosclerosis and uncomplicated plaques had significantly higher serum anti-actin IgG reactivity than those with complicated plaques (P = 0.048 by Student's t-test). Our findings suggest that actin is an autoantigenic molecule of potential clinical interest in carotid atherosclerosis.

Echinococcus granulosus-specific T-cell lines derived from patients at various clinical stages of cystic echinococcosis.

To investigate the role of T lymphocytes in the immune response to Echinococcus granulosus, using sheep hydatid fluid (SHF) and antigen B (AgB), we generated T-cell lines from patients with active, transitional and inactive hydatid cysts. We established 16 T-cell lines, eight specific to SHF and eight specific to AgB. At surface phenotyping 88-98% of cells displayed the helper/inducer CD4 antigen. In all patients, at all clinical stages of hydatid cyst disease, T-cell stimulation with SHF and AgB invariably amplified a large number of almost identical Vbeta subfamily fragments. Irrespective of antigen-specificity, the two cell lines from the patient with an inactive cyst had a Th1 profile, because they exclusively expressed and produced IFN-gamma. Conversely, the T-cell lines derived from the seven patients with active and transitional hydatid cysts had mixed Th1/Th2 and Th0 clones. The functional characteristics of the 16 T-cell lines differed markedly in the various clinical stages of cystic echinococcosis, thus providing new in vitro evidence that Th1 lymphocytes contribute decisively to the inactive stage of hydatid disease, Th2 lymphocytes in the active and transitional stages. The parasite-specific T-cell lines, especially the two Th1 lines from the patient with an inactive cyst, may help identify Th1 protective epitopes on SHF and AgB.

Critical points in the immunodiagnosis of cystic echinococcosis in humans.

This study discusses the immunodiagnosis of cystic echinococcosis (ce, caused by Echinococcus granulosus). The detection by immunoblotting of antibodies specific for the 8 kDa subunit of antigen B and in particular the IgG4 subclass expression, seems the most promising serodiagnostic tool. Despite the development of molecular methods, nowadays there is no standard, highly sensitive, and specific test available for antibody detection in CE. Furthermore, because serological tests can give only a limited support to clinical findings there is a clear need for new advances in immunodiagnosis of E. granulosus infection.

Molecular and immunological characterization of the C-terminal region of a new Echinococcus granulosus Heat Shock Protein 70.

By screening an expression library of Echinococcus granulosus with IgE from sera of patients with cystic echinococcosis (CE) and allergic reactions, we isolated the C-terminal region of a new heat shock protein (HSP)70 of E. granulosus. The protein, named Eg2HSP70, has close homology with the C-terminal region of Dermatophagoides farinae and human HSP70. We investigated the humoral and cell-mediated immune responses to this antigen in patients with CE grouped according to the presence of allergic reactions. Immunoblotting detected total IgG, IgG4 and IgE specific to Eg2HSP70 (83% of sera contained IgG, 31% IgG4 and 57% IgE). No significant difference was found in immunoglobulin percentages according to the presence of allergic reactions. Immunoblotting inhibition showed that no IgG or IgE specific to Eg2HSP70 cross-reacted with D. farinae or human HSP70. Eg2HSP70-stimulated PBMC from 26 patients produced significantly greater amounts of TNF-alpha, IFN-gamma, and IL-10 than unstimulated cultures in all patients, irrespective of the presence of allergic reactions (P < 0.05). They also produced significantly greater amounts of IL-4 than unstimulated cultures exclusively in patients with allergic reactions (P < 0.05). These findings show that Eg2HSP70 is a new antigenic molecule inducing both B and T cell responses.

Cytokine expression in circulating T lymphocytes from patients undergoing carotid endarterectomy.

AIM: We investigated a possible relationship of cytokine expression and phenotype features of circulating T lymphocytes with the histological type of atherosclerotic plaque removed during carotid endarterectomy. METHODS: Peripheral blood samples were taken from 20 patients with carotid atherosclerosis and from 8 healthy blood donors. Patients were divided into 2 groups according to the histological type of their atherosclerotic plaques (types V and VI). Expression of intracellular tumor necrosis factor (TNF)-alpha, interferon (IFN)-gamma, interleukin-4 (IL-4), and of surface antigens (CD4, CD8, CD45RA, CD45RO, T cell receptor (TCR) alpha/beta, TCR gamma/delta) in circulating T lymphocytes was determined by 3-colour cytofluorimetric analysis. RESULTS: The percentage of T lymphocytes primed for TNF-alpha, IFN-gamma and IL-4 was higher in blood samples from patients than from healthy subjects; the difference was statistically significant for TNF-alpha-producing cells (p=0.01). In patients, the percentage of TNF-alpha-producing cells was significantly higher in the CD4+ subset than in the CD8+ subset (p=10(-4)). The percentage of TNF-alpha-, IFN-gamma- and IL-4-primed cells was higher in patients with type VI plaques (complicated lesions) than in patients with type V plaques (less complicated lesions). The difference was statistically significant for TNF-alpha-primed cells (p=0.05). No statistically significant differences were found in T cell phenotype features among patients or between patients and healthy subjects. CONCLUSION: Our results suggest a relationship between the percentage of circulating T lymphocytes expressing TNF-alpha and possibly IFN-gamma and IL-4 and the histological type of atherosclerotic plaque in patients with carotid artery disease.

Long-term serological evaluation of patients with cystic echinococcosis treated with benzimidazole carbamates.

Seeking better immunological markers indicating the long-term outcome of cystic echinococcosis (CE) after chemotherapy we studied 23 patients receiving albendazole, clinically followed for 8 years, and grouped ultrasonographically according to therapeutic outcome. Antibody responses against a partially purified fraction of hydatid fluid (HFF) and antigen B (AgB) were evaluated by indirect haemagglutination (IHA), ELISA and immunoblotting (IB). Although IHA titres varied over the course of treatment, differences in mean antibody titres to HFF between groups were significant only at 4 years (P = 0.031). IgG isotype expression remained unchanged during follow-up whereas IgE expression decreased in patients with cured or stable disease. AgB disclosed higher IgG4 expression (P < 10(-4); P = 0.025) and lower IgG1 expression than HFF (P < 10(-4); P = 0.022). IHA antibody titres were higher in patients with progressive than in those with cured or stable disease, even in those with the same cyst type. ELISA isotype profiles differed between groups, particularly for type CE 3, 4 and 5 cysts: higher serum IgG1 and IgG3, lower IgG4 and IgE in patients with cured or stable disease. Although combined serological testing provides scarce information on the long-term outcome of CE after chemotherapy it may be useful for reviewing in a retrospective study the outcome of a cyst and for assessing the host-parasite relationship.

Immunological characterization of Echinococcus granulosus cyclophilin, an allergen reactive with IgE and IgG4 from patients with cystic echinococcosis.

By immunological screening of a cDNA library derived from protoscoleces of Echinococcus granulosus with IgE from patients with cystic echinococcosis (CE) and allergic manifestations, we isolated a protein identical to E. granulosus cyclophilin. The protein, named EA21, has close homology with Malassezia furfur cyclophilin allergen (Mal f 6) and with human cyclophilin. Using immunoblotting (IB) with a polyclonal antibody specific to EA21, we identified E. granulosus cyclophilin both in protoscoleces and in sheep hydatid fluid. Of the 58 sera from patients with CE, 29 (50%) were IgE positive to EA21, whereas, despite the high sequence homology, none were IgE positive to Mal f 6 or human cyclophilin. Only 26 of the 58 patients (45%) had IgG specific to EA21, whereas all patients (100%) had IgG specific to Mal f 6 and human cyclophilin. IB analysis showed that serum IgE-binding reactivity to EA21 differed significantly in patients with and without allergic reactions (20 of 25, 80% versus nine of 33, 27%; P < 10(-4)). Conversely, five of the 25 patients who had CE-related allergic manifestations (20%) and 21 of the 33 who did not (63%) had specific IgG4 (P = 10(-3)) and total IgG to EA21. EA21 induced a proliferative response in 15 of 19 (79%) patients' PBMC regardless of the allergic manifestations, but it induced no IL-4 production. Overall, these findings suggest that E. granulosus cyclophilin is a conserved, constitutive, parasite protein that does not cross-react with cyclophilins from other organisms and is involved in the allergic symptoms related to CE.

Elongation factor 1 beta/delta of Echinococcus granulosus and allergic manifestations in human cystic echinococcosis.

Allergic reactions, such as urticaria, itching and anaphylactic shock, often complicate the course of cystic echinococcosis (CE). To investigate the role of the IgE-immunoreactive recombinant Echinococcus granulosus elongation factor-1 beta/delta (EgEF-1 beta/delta) in the allergic disorders during CE we determined humoral and cell-mediated responses to this antigen in patients with CE grouped according to the clinical presence or absence of allergic reactions. Immunoblotting analysis showed that serum IgE-binding reactivity to EgEF-1 beta/delta differed significantly in patients with and without allergic reactions (38 of 42, 90% vs. 31 of 56, 56%; P < 10(-4)). EgEF-1 beta/delta induced a proliferative response in 14 of 19 (74%) patients' peripheral blood mononuclear cells (PBMC) irrespective of the allergic manifestations and skewed Th1/Th2 cytokine activation towards a preferentially Th2 polarization. Epitope mapping identified an immunodominant epitope of 18 residues with 78% identity and 89% similarity with an IgE-immunoreactive Strongyloides stercoralis antigen. Overall these findings suggest that EgEF-1 beta/delta is an allergenic molecule that may be a general marker of the intensity of CE immune response and that could lead to a deeper understanding of the specific antigen-induced mechanisms underlying allergic reactions in the human host.

Modulation of human immune response by Echinococcus granulosus antigen B and its possible role in evading host defenses.

By directly suppressing the function of certain immune cell subsets and by stimulating other cell populations related to immunopathology, parasite-derived substances play an important role in the chronic establishment of parasitic disease. Our objective was twofold: (i) to investigate further the role of Echinococcus granulosus antigen B (AgB) in the human early inflammatory response by determining its effect on polymorphonuclear cell (PMN) random migration, chemotaxis, and oxidative metabolism and (ii) to determine its action in acquired immunity by evaluating AgB and sheep hydatid fluid (SHF)-driven Th1 (gamma interferon [IFN-gamma] and interleukin 12 [IL-12]) and Th2 (IL-4 and IL-13) cytokine production by peripheral blood mononuclear cells (PBMC) from 40 patients who had cured or stable or progressive cystic echinococcosis. AgB significantly inhibited PMN recruitment but left their random migration and oxidative metabolism unchanged. Patients' PBMC stimulated with AgB produced IL-4 and IL-13 but did not produce IL-12. They also produced significantly lower IFN-gamma concentrations than did PBMC stimulated with SHF (P = 10(-5)). AgB skewed the Th1/Th2 cytokine ratios towards a preferentially immunopathology-associated Th2 polarization, predominantly in patients with progressive disease. AgB-stimulated patients' PBMC also proliferated less than SHF-stimulated PBMC (P = 9 x 10(-3)). In vitro Th2 cytokine production was reflected in vivo by elevated specific immunoglobulin E (IgE) and IgG4 antibodies binding to AgB. These findings confirm that AgB plays a role in the escape from early immunity by inhibiting PMN chemotaxis. They also add new information on the host-parasite relationship, suggesting that AgB exploits the activation of T helper cells by eliciting a nonprotective Th2 cell response.