RESUMO
Here we describe the cloning and characterization of the Schistosoma mansoni Alkaline Phosphatase (SmAP), previously identified in the tegument of adult worms. SmAP encodes a complete sequence composed of 536 amino acids containing an N-terminal signal peptide, five N-glycosylation sites, and a GPI anchor signal, similar to that described for mammalian orthologs. Real-time RT-PCR and Western blot experiments suggest a rapid translation as soon as cercariae are transformed into schistosomula. Immunolocalization analysis shows that the protein is widely distributed in the worm tissues, with increased concentration in the vitelline glands of female parasites. Furthermore, the surface localization of this enzyme was quantitatively supported by its enzymatic activity in live ex vivo or cultured parasites throughout the life cycle stages. The fact that cercariae accumulate large amounts of SmAP mRNA, which rapidly translates into protein upon schistosomula transformation, indicates it may have an important role in host invasion.
Assuntos
Fosfatase Alcalina/genética , Regulação Enzimológica da Expressão Gênica , Schistosoma mansoni/enzimologia , Fosfatase Alcalina/química , Fosfatase Alcalina/metabolismo , Animais , Sequência de Bases , Western Blotting , Cricetinae , DNA Complementar/química , DNA de Helmintos/química , Feminino , Estágios do Ciclo de Vida/genética , Masculino , Microscopia Confocal , Microscopia de Fluorescência , Reação em Cadeia da Polimerase em Tempo Real , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Schistosoma mansoni/genética , Schistosoma mansoni/crescimento & desenvolvimento , Alinhamento de Sequência , Transcrição GênicaRESUMO
Here we describe the cloning and characterization of the Schistosoma mansoni Alkaline Phosphatase(SmAP), previously identified in the tegument of adult worms. SmAP encodes a complete sequence composedof 536 amino acids containing an N-terminal signal peptide, five N-glycosylation sites, and a GPIanchor signal, similar to that described for mammalian orthologs. Real-time RT-PCR and Western blotexperiments suggest a rapid translation as soon as cercariae are transformed into schistosomula. Immunolocalizationanalysis shows that the protein is widely distributed in the worm tissues, with increased concentration in the vitelline glands of female parasites. Furthermore, the surface localization of thisenzyme was quantitatively supported by its enzymatic activity in live ex vivo or cultured parasites throughout the life cycle stages. The fact that cercariae accumulate large amounts of SmAP mRNA, which rapidly translates into protein upon schistosomula transformation, indicates it may have an important role in host invasion.
Assuntos
Animais , Aminoácidos/classificação , Fosfatase Alcalina , Schistosoma mansoni/anatomia & histologia , Schistosoma mansoni/classificação , Schistosoma mansoni/genética , Schistosoma mansoni/ultraestrutura , Glicosilação , Vetores GenéticosRESUMO
Schistosomes undergo various morphological and metabolic changes during their development, reflected in a finely tuned regulation of protein and/or gene expression. The mechanisms involved in the control of gene expression during the development of the parasite are not understood. Two actin genes had been previously cloned and observed to be differentially expressed during the maturation of the parasite. The SmAct gene contains four putative cis-regulatory elements (TATA-, CCAAT-, E- and CArG-boxes). Our objective was to investigate in greater detail the expression pattern of two actin genes and verify if the binding of nuclear proteins to the promoter elements of SmAct correlated with the expression profile observed. We detected little variation in the expression of actin genes during the first seven days of schistosomula culture in vitro. However, we observed significantly higher levels of expression in males compared to female adults. CArG and CCAAT elements bound to a greater extent and formed distinct complexes with male in comparison to female nuclear extracts. In contrast, female extracts bound weakly to the E-box probe while no binding was observed with male extracts. Taken together these results describe cis-acting elements that appear to be involved in sexually regulated gene expression in Schistosoma mansoni.
Assuntos
Proteínas de Ligação a DNA/análise , Regulação da Expressão Gênica no Desenvolvimento/genética , Regiões Promotoras Genéticas , Proteínas Repressoras/análise , Schistosoma mansoni/genética , Animais , Sequência de Bases , Northern Blotting , Proteínas Estimuladoras de Ligação a CCAAT/análise , Feminino , Masculino , Dados de Sequência Molecular , Sequências Reguladoras de Ácido Nucleico , Schistosoma mansoni/enzimologia , Schistosoma mansoni/crescimento & desenvolvimento , Proteína de Ligação a TATA-Box/análiseRESUMO
Schistosomes undergo various morphological and metabolic changes during their development, reflected in a finely tuned regulation of protein and/or gene expression. The mechanisms involved in the control of gene expression during the development of the parasite are not understood. Two actin genes had been previously cloned and observed to be differentially expressed during the maturation of the parasite. The SmAct gene contains four putative cis-regulatory elements (TATA-, CCAAT-, E- and CArG-boxes). Our objective was to investigate in greater detail the expression pattern of two actin genes and verify if the binding of nuclear proteins to the promoter elements of SmAct correlated with the expression profile observed. We detected little variation in the expression of actin genes during the first seven days of schistosomula culture in vitro. However, we observed significantly higher levels of expression in males compared to female adults. CArG and CCAAT elements bound to a greater extent and formed distinct complexes with male in comparison to female nuclear extracts. In contrast, female extracts bound weakly to the E-box probe while no binding was observed with male extracts. Taken together these results describe cis-acting elements that appear to be involved in sexually regulated gene expression in Schistosoma mansoni
Assuntos
Animais , Masculino , Feminino , Proteínas de Ligação a DNA , Regulação da Expressão Gênica , Regiões Promotoras Genéticas , Schistosoma mansoni , Sequência de Bases , Northern Blotting , Proteínas Estimuladoras de Ligação a CCAAT , Dados de Sequência Molecular , Proteínas Nucleares , Sequências Reguladoras de Ácido Nucleico , Reação em Cadeia da Polimerase Via Transcriptase Reversa , RNA Mensageiro , Schistosoma mansoni , Proteína de Ligação a TATA-Box/análise , Fatores de TranscriçãoRESUMO
A histopathological and immunophenotypic study was performed on the spleen of patients with hepatosplenic (HS) schistosomiasis mansoni. Morphological data demonstrated that all HS patients presented features related to Schistosoma mansoni-induced splenomegaly, such as red pulp congestion and atrophy/hyperplasia of white pulp. The morphological diversity of the white pulp seems to be associated with the expansion of activated CD4+ T-cell subpopulation. The data obtained suggest that the spleen is an important site for T-cell activation during severe chronic infection with S. mansoni. In addition, we have compared the cell populations/subpopulations presented in the peripheral blood with that observed in the spleen of patients with HS schistosomiasis mansoni. We observed a significant increase in the percentage of activated CD4+HLA-DR+ and CD8+HLA-DR+ T cells in both the spleen and the peripheral blood of HS patients in comparison with noninfected individuals (NOR). These data suggest an exchange of cells between these two compartments. However, we observed normal expression of the CD28 molecule by CD8+ T cells in the spleen, despite a lower percentage of these cells in the peripheral blood. This finding supports the hypothesis that the decrease in CD28 expression, by CD8+ cells, is an event that takes place outside the spleen during human schistosomiasis infection. The most important conclusion is the fact that the analysis of T-cell activation in the peripheral blood reflects the major immunological reactivity that occurs in the spleen during human schistosomiasis and that the morphological aspects of the spleen may reflect the functional activity of T cells. The specificities of T cells and the roles they may play in the pathogenesis during chronic schistosomiasis now need to be determined.
Assuntos
Ativação Linfocitária , Esquistossomose mansoni/imunologia , Baço/imunologia , Subpopulações de Linfócitos T/imunologia , Adolescente , Adulto , Células Sanguíneas/imunologia , Antígenos CD28/análise , Movimento Celular , Feminino , Humanos , Imunofenotipagem , Fígado/patologia , Masculino , Pessoa de Meia-Idade , Esquistossomose mansoni/patologia , Baço/citologia , Baço/patologia , Subpopulações de Linfócitos T/classificaçãoRESUMO
Sm14 is a 14-kDa vaccine candidate antigen from Schistosoma mansoni that seems to be involved in cytoplasmic trafficking of fatty acids. Although schistosomes have a high requirement for lipids, they are not able to synthesize fatty acids and sterols de novo. Thus, they must acquire host lipids. In order to determine whether Sm14 is present in different stages of the life cycle of the parasite, we performed RT-PCR. Sm14 mRNA was identified in all stages of the life cycle studied, mainly schistosomulum, adult worm and egg. Additionally, we used a rabbit anti-Sm14 polyclonal antibody in an indirect immunofluorescence assay to localize Sm14 in adult worm sections. The basal lamella of the tegument and the gut epithelium were strongly labeled. These tissues have a high flow of and demand for lipids, a finding that supports the putative role of Sm14 as an intracellular transporter of fatty acids from host cells.
Assuntos
Proteínas de Transporte/análise , Proteínas de Helminto/análise , Proteínas de Membrana Transportadoras , Proteínas de Neoplasias , Proteínas do Tecido Nervoso , Schistosoma mansoni/metabolismo , Animais , Anticorpos Anti-Helmínticos/imunologia , DNA Complementar , Proteínas de Transporte de Ácido Graxo , Proteína 7 de Ligação a Ácidos Graxos , Proteínas de Ligação a Ácido Graxo , Feminino , Técnica Indireta de Fluorescência para Anticorpo , Expressão Gênica , Proteínas de Helminto/genética , Proteínas de Helminto/fisiologia , Estágios do Ciclo de Vida , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Vacinas Protozoárias/imunologia , Coelhos , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Schistosoma mansoni/genética , Schistosoma mansoni/crescimento & desenvolvimento , Esquistossomose mansoni/imunologiaRESUMO
Sm14 is a 14-kDa vaccine candidate antigen from Schistosoma mansoni that seems to be involved in cytoplasmic trafficking of fatty acids. Although schistosomes have a high requirement for lipids, they are not able to synthesize fatty acids and sterols de novo. Thus, they must acquire host lipids. In order to determine whether Sm14 is present in different stages of the life cycle of the parasite, we performed RT-PCR. Sm14 mRNA was identified in all stages of the life cycle studied, mainly schistosomulum, adult worm and egg. Additionally, we used a rabbit anti-Sm14 polyclonal antibody in an indirect immunofluorescence assay to localize Sm14 in adult worm sections. The basal lamella of the tegument and the gut epithelium were strongly labeled. These tissues have a high flow of and demand for lipids, a finding that supports the putative role of Sm14 as an intracellular transporter of fatty acids from host cells
Assuntos
Animais , Masculino , Feminino , Camundongos , Coelhos , Proteínas de Helminto , Schistosoma mansoni , Esquistossomose mansoni , Anticorpos Anti-Helmínticos , Proteínas de Transporte , DNA Complementar , Técnica Indireta de Fluorescência para Anticorpo , Expressão Gênica , Proteínas de Helminto , Estágios do Ciclo de Vida , Camundongos Endogâmicos BALB C , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Schistosoma mansoni , VacinasRESUMO
People infected with schistosomes may present with a variety of clinical manifestations ranging from the relatively asymptomatic intestinal (INT) form to the hepatointestinal (HI) or hepatosplenic (HS) forms characterized by hepatomegaly and hepatosplenomegaly with severe portal hypertension, respectively. Flow cytometry analyses were used to evaluate the contribution of apoptosis in specific cell populations from schistosomiasis patients to the development of the different clinical forms of the disease. The results showed that cell death induced by combinations of specific antigen and cytokines corresponds with specific clinical presentations. It was shown that soluble egg antigen (SEA) increased the level of apoptosis only in T cells from INT patients. Stimulation with soluble lung worm antigen preparation (SLAP) did not induce significant differences in the levels of apoptosis in T cells from the patients with the different clinical forms of schistosomiasis. These results suggest for the first time that apoptosis plays an important role in the modulation of the anti-SEA response in INT patients.
Assuntos
Apoptose/imunologia , Leucócitos Mononucleares/imunologia , Schistosoma mansoni/imunologia , Esquistossomose mansoni/imunologia , Adolescente , Adulto , Idoso , Animais , Antígenos de Helmintos/farmacologia , Linfócitos B/efeitos dos fármacos , Linfócitos B/imunologia , Células Cultivadas , Criança , Citocinas/farmacologia , Fezes/parasitologia , Feminino , Humanos , Leucócitos Mononucleares/efeitos dos fármacos , Masculino , Pessoa de Meia-Idade , Esquistossomose mansoni/sangue , Esquistossomose mansoni/parasitologia , Subpopulações de Linfócitos T/efeitos dos fármacos , Subpopulações de Linfócitos T/imunologiaRESUMO
Vaccination of mice with radiation-attenuated cercariae of Schistosoma mansoni induces a high level of protection against challenge with normal larvae. The immune effector mechanism, which operates in the lungs, is a cell-mediated delayed-type hypersensitivity response and involves the formation of a tight focus of mononuclear cells around embolised larvae. CD4+ T cells with Th1 characteristics are a major component of the infiltrate. They secrete abundant interferon gamma (IFN gamma) upon antigen stimulation in vitro, whilst in vivo neutralisation of the cytokine results in 90% abrogation of immunity. IFN gamma can induce a large number of genes and an attempt has been made to identify the ones which are essential components of the effector mechanism. Inducible nitric oxide synthase (iNOS) is such a candidate and nitric oxide (NO) is produced by cultures of airway leucocytes from the lungs of vaccinated mice post-challenge. However, the continued resistance of mice with a disrupted iNOS gene indicates that NO has only a minor role in the protective response. Mice with a disrupted IFN gamma receptor gene have been used to dissect the role of the cytokine. After vaccination and challenge, CD4+ T cells from the pulmonary interstitium have reduced levels of ICAM-1 and LFA-1 expression, compared to wild-type animals, which coincides with a reduced cohesiveness of foci. However, immunity is not significantly impaired in mice with a disrupted ICAM-1 gene, and focus formation is normal. Similarly, a role has not been found for CD2/CD48 interactions in cell aggregation. Possible IFN gamma-inducible molecules yet to be fully investigated include other ligand-receptor pairs, chemokines, and tumour necrosis factor alpha.
Assuntos
Citocinas/fisiologia , Interferon gama/fisiologia , Pulmão/imunologia , Schistosoma mansoni/patogenicidade , Esquistossomose mansoni/imunologia , Animais , CamundongosRESUMO
The role of different cytokines in the peripheral blood mononuclear cell (PBMC) proliferative response and in in vitro granuloma formation was evaluated in a cross-sectional study with patients with the different clinical forms and phases of Schistosoma mansoni infection, as well as a group of individuals "naturally" resistant to infection named normal endemic (NE). The blockage of IL-4 and IL-5 using anti-IL-4 and anti-IL-5 antibodies significantly reduced the PBMC proliferative response to soluble egg (SEA) and adult worm (SWAP) antigens in acute (ACT), chronic intestinal (INT) and hepatosplenic (HS) patients. Similar results were obtained in the in vitro granuloma formation. Blockage of IL-10 had no significant effect on either assay using PBMC from ACT or HS. In contrast, the addition of anti-IL-10 antibodies to PBMC cultures from INT patients significantly increased the proliferative response to SEA and SWAP as well as the in vitro granuloma formation. Interestingly, association of anti-IL-4 and anti-IL-10 antibodies did not increase the PBMC proliferative response of these patients, suggesting that IL-10 may act by modulating IL-4 and IL-5 secretion. Addition of recombinant IL-10 decreased the proliferative response to undetectable levels when PBMC from patients with the different clinical forms were used. Analysis of IFN-gamma in the supernatants showed that PBMC from INT patients secreted low levels of IFN-gamma upon antigenic stimulation. In contrast, PBMC from NE secreted high levels of IFN-gamma. These data suggest that IL-10 is an important cytokine in regulating the immune response and possibly controlling morbidity in human schistosomiasis mansoni, and that the production of IFN-gamma may be associated with resistance to infection.
Assuntos
Citocinas/fisiologia , Imunidade Inata/fisiologia , Schistosoma mansoni/patogenicidade , Esquistossomose mansoni/imunologia , Animais , Humanos , Interferon gama , Interleucina-10 , Interleucina-11 , Interleucina-4RESUMO
The presence of naturally portacaval shunts has been investigated in the vasculature of normal and Schistosoma mansoni-infected Rattus rattus. Using the technique of injecting Polystyrene microspheres in the superior mesenteric vein, we demonstrated that the presence of adult schistosomes in the lungs of R. rattus was not due to an innate anomaly of the rat vasculature but resulted from the formation of portacaval shunts during infection. In rats harbouring a bisexual infection, microspheres were only detected in the lungs from week 7. The development and increasing size of the shunts were maximal between weeks 7 and 10 and coincident with the translocation of adult worms from the portal tract to the lungs. At weeks 20-25, only 1-2% of the microspheres were recovered from the lungs, suggesting that the portacaval anastomoses have regressed due to reduction in portal hypertension after worm translocation. R. rattus with a male-only schistosome infection harboured adult worms in the lungs, indicating that the development of shunts does not solely depend upon egg deposition in the liver to generate hypertension. The relationships between the presence of the schistosomes in the lungs, the portacaval shunting and the resistance to reinfection is discussed.
Assuntos
Pulmão/parasitologia , Muridae/parasitologia , Veia Porta/fisiopatologia , Schistosoma mansoni/fisiologia , Animais , Feminino , Guadalupe , Hemodinâmica , Hipertensão Portal/parasitologia , Hipertensão Portal/fisiopatologia , Fígado/parasitologia , Pulmão/fisiologia , Masculino , Microesferas , Muridae/fisiologia , Contagem de Ovos de Parasitas , Perfusão , Veia Porta/parasitologia , Ratos , Fatores de TempoRESUMO
The role of diferent cytokines in the peripheral blood mononuclear cell (PBMC) proliferative response and in in vitro granuloma formation was evaluated in a cross-sectional study with patients with the different clinical forms and phases of Schistosoma mansoni infection, as well as a group of individuals "naturally" resistant to infection named normal endemic (NE). The blockage of IL-4 and IL-5 using anti-IL-4 and anti-IL-5 antibodies significantly reduced the PBMC proliferative response to soluble egg (SEA) and adult worm (SWAP) antigens in acute (ACT), chronic intestinal (INT) and hepatosplenic (HS) patients. Similar esults were obtained in the in vitro granuloma formation. Blockage of IL-10 had no significant effect on either assay using PBMC from ACT or HS. In contrast, the addition of anti-IL-10 antibodies to PBMC cultures from INT patients significantly increased the proliferative response to SEA and SWAP as well as the in vitro granuloma formation. Interestingly, association of anti-IL-4 and anti-IL-10 antibodies did not increase the PBMC proliferative response of these patients, suggesting that IL-10 may act by modulating IL-4 and IL-5 secretion. Addition of recombinant IL-10 decreased the proliferative response to undetectable levels when PBMC from patients with the different clinical forms were used. Analysis of IFN-gamma in the supernatants showed that PBMC from INT patients secreted low levels of IFN-gamma upon antigenic stimulation. In contrast, PBMC from NE secreted high levels of IFN-gamma. These data suggest that IL-10 is an important cytokine in regulating the immune response and possibly controlling morbidity in human schistosomiasis mansoni, and that the production of IFN-gamma may be associated with resistance to infection.
Assuntos
Humanos , Citocinas/fisiologia , Imunidade Inata/fisiologia , Schistosoma mansoni/patogenicidade , Esquistossomose mansoni/imunologia , Esquistossomose mansoni/fisiopatologia , Interferon gama , Interleucina-10 , Interleucina-11 , Interleucina-4RESUMO
The generation of expressed sequenced tags (ESTs) depends on the arbitrary selection of individual cDNA clones from libraries. The efficiency of this process reflects the clonal structure of the library used and can be significantly increased using size selected, directional, normalized cDNA libraries. This strategy, however, is not readily applicable when mRNA is limiting, as is the case in the study of complex microorganisms such as parasites, fetal tissues or tumor biopsies. We show here that the construction and systematic sequencing of minilibraries of cDNAs produced by arbitrarily primed PCR provides an alternative means of efficiently generating ESTs in situations where only nanogram quantities of RNA are available. This methodology greatly compensates for unequal message abundance, avoids the need for complex library construction, is equally applicable to the analysis of abundant or rare biological material and is ideally suited to multicenter programmes.
Assuntos
Biblioteca Gênica , Reação em Cadeia da Polimerase/métodos , RNA Mensageiro/química , Schistosoma mansoni/genética , Sitios de Sequências Rotuladas , Animais , Primers do DNA , DNA Complementar/química , DNA Complementar/genética , Bases de Dados Factuais , Camundongos , Dados de Sequência Molecular , RNA Mensageiro/genética , DNA Polimerase Dirigida por RNA/química , DNA Polimerase Dirigida por RNA/genética , Homologia de Sequência do Ácido NucleicoRESUMO
Ninety-eight women-infant pairs were followed for up to 50 weeks in the northern part of Guadalajara, Mexico, from August 1986 to July 1987 as part of a community-based, prospective study of the relation between infant feeding patterns and enterotoxigenic Escherichia coli producing heat-labile toxin (LT-ETEC) diarrheal disease. Strictly formula-fed children had an incidence of diarrhea over three times that of strictly breast-fed infants and twice that of breast-fed and supplementally fed children. Strictly formula-fed infants colonized by LT-ETEC were symptomatic for diarrhea nearly three times as often as strictly breast-fed infants and twice as often as infants receiving a mixed diet. The fitting of parametric hazard models to durations until LT-ETEC colonization revealed that the hazard for the first colonization was time invariant. The hazard of diarrhea increased by 400-500% during the rainy season or among children 3 months of age or older who received avena, a barley drink. The best-fitting hazard models to durations until symptomatic expression of LT-ETEC infection all increased through time. This hazard was inversely impacted by the overall amount of LT-ETEC-specific, immunoglobulin A antibodies the infant received via the mother's breast milk and by the provision of traditional medicinal teas.
Assuntos
Toxinas Bacterianas/biossíntese , Aleitamento Materno , Diarreia Infantil/epidemiologia , Enterotoxinas/biossíntese , Infecções por Escherichia coli/epidemiologia , Proteínas de Escherichia coli , Saúde da População Urbana , Toxinas Bacterianas/análise , Estudos de Coortes , Diarreia Infantil/microbiologia , Enterotoxinas/análise , Escherichia coli/metabolismo , Infecções por Escherichia coli/microbiologia , Feminino , Humanos , Imunoglobulina A/análise , Lactente , Alimentos Infantis , Recém-Nascido , México/epidemiologia , Leite Humano/imunologia , Leite Humano/microbiologia , Modelos de Riscos Proporcionais , Estudos Prospectivos , Fatores de Risco , Estações do Ano , Fatores SocioeconômicosRESUMO
In C57Bl/6 strain mice vaccinated with radiation-attenuated cercariae of Schistosoma mansoni immune elimination of challenge parasites occurs in the lungs. Leucocytes were recovered from the lungs of such mice by bronchoalveolar lavage and cultured in vitro with larval antigen; the profile of cytokines released was then analyzed. From 14 days after vaccination, BAL cultures contained infiltrating lymphocytes which produced abundant quantities of IFN-g and IL-3. Challenge of vaccinated mice resulted in a second influx of IFN-g and IL-3--producing cells, earlier than after vaccination or in the appropriate controls. Ablation studies revealed that CD4+ T cells were the source of IFN-g. The timing of cytokine production after vaccination, and challenge was coincident with the phases of macrophage activation previously reported. At no time could lymphocytes in BAL cultures be stimulated to proliferate with either larval Ag or mitogen, in contrast to splenocytes from the same mice. Furthermore, T cell growth factor activity was not detected in BAL cultures stimulated with Ag. We suggest that the lymphocytes recruited to the lungs are memory/effector cells. When Ag released from challenge schistosomula is presented to these cells, they respond by secreting cytokines which mediate the formation of cellular aggregates around the parasites, blocking their onward migration.
Assuntos
Pulmão/parasitologia , Schistosoma mansoni/imunologia , Esquistossomose mansoni/imunologia , Subpopulações de Linfócitos T/imunologia , Vacinação , Animais , Anticorpos Monoclonais/imunologia , Anticorpos Monoclonais/farmacologia , Líquido da Lavagem Broncoalveolar/citologia , Células Cultivadas , Interferon gama/antagonistas & inibidores , Interferon gama/fisiologia , Larva , Pulmão/imunologia , Ativação de Macrófagos , Camundongos , Camundongos Endogâmicos C57BL , Modelos Biológicos , Schistosoma mansoni/crescimento & desenvolvimento , Schistosoma mansoni/efeitos da radiação , Esquistossomose mansoni/prevenção & controleRESUMO
In C57Bl/6 strain mice vaccinated with radiation-attenuated cercariae of Schistosoma mansoni immune elimination of challenge parasites occurs in the lungs. Leococytes were recovered from the lungs of such mice by bronchoalveolar lavage and cultured in vitro with larval antigen; the profile of cytokines released was then analyzed. From 14 days after vaccination, BAL cultures contained infiltrating lymphocytes wich produced abundant quantitties of IFN-g and IL-3. Challenge of vaccinated mice resulted in a second influx of IFN-g nd IL-3- producing cells, earlier than after vaccination or in the appropriate contropls. Ablation studies revealed that CD4+ T cells were the source of IFN-g. The timing of cytokine production after vaccination, and challenge was coincident with the phases of macrophage activation previously reported. At no time could lymphocytes in BAL cultures to stimulated to proliferate with either larval Ag or mitogen, in contrast to splenocytes from the same mice. Furthermore, T cell growth factor activity was not detected in BAL cultures stimulated with Ag. We suggest that the lymphocytes recruited to the lungs are memory/effector cells, When Ag. released challenge schistosomula is presented to these cells, they respond by secreting cytokines wich mediate the formation of cellular aggregates around the parasites, blocking their onward migration