Trypanosoma cruzi: identification of a galactose-binding protein that binds to cell surface of human erythrocytes and is involved in cell invasion by the parasite.

Trypanosoma cruzi must invade mammalian host cells to replicate and complete its life cycle. Almost all nucleated mammalian cells can be invaded by the parasite following a receptor-ligand recognition as an early prerequisite. In this work, we describe a 67-kDa lectin-like glycoprotein that binds to desialylated human erythrocyte membranes in a galactose-dependent way. This protein is present on the parasite surface in both infective and non-infective stages of T. cruzi. More interestingly, we demonstrate by lectin-immuno-histochemistry assays that the 67kDa protein is involved in the recognition of host-cell receptors in mouse cardiac tissue and human cardiac aortic endothelium and mammary artery tissue. Moreover, antibodies against the 67kDa glycoprotein inhibit in vitro host-cell invasion by 63%. These data suggest that the 67kDa glycoprotein in vivo is needed for host-cell invasion by T. cruzi.

Antibody maturation in Trypanosoma cruzi-infected rats.

The study of antibody avidity changes during infection has improved the understanding of the pathologic processes involved in several infectious diseases. In some infections, like toxoplasmosis, this information is being used for diagnostic purposes. Results of the evolution of antibody avidity for different specific antigens in Trypanosome cruzi-infected rats are presented. A Western blotting technique, combined with avidity analysis to identify antigens that elicit high-avidity antibodies, is suggested. In this system, antibodies showed high avidity values only during the chronic phase of infection and only in relation to antibodies against 21-, 33-, 41-, 42-, 56-, 58-, 66-, and 72-kDa antigens. Finally, a 97-kDa T. cruzi antigen, which was recognized by high-avidity antibodies and occurred in noninfected rats, was identified. These results allow us to evaluate the different antigens in chagasic infection. Our results show that with the correct choice of antigen it is possible to detect differences in maturation of antibodies and to discriminate, in an experimental model, between recent (acute) and chronic infections.

[Association between soybean dust exposure, allergic sensitivity and profile of respiratory symptoms]. / Asociación entre exposición a polvo de soja, sensibilidad alérgica y perfil de síntomas respiratorios.

The purpose of this study was to correlate soybean dust (SD) exposure, skin reactivity to soybean hull (SH) allergens, and symptoms of asthma and/or allergic rhinitis. A group of 365 subjects with asthma and/or allergic rhinitis and a control group of 50 individuals without respiratory symptoms were studied. The level of exposure to SD is defined as follows: 1) direct (DE); 2) indirect (ID), and 3) urban (UE). All subjects completed standard questionnaires. Skin tests with a SH extract and with common allergens were performed by the prick technique (SPT). Fifty-six (15.3%) patients and no subjects from control group had positive SPT (histamine index > or = 0.5) with a SH allergen extract. The percentages of positive SPT to SH extract were 38.7%, 20.3% and 8.4% in subjects with DE, IE and UE, respectively (p < 0.001). Monosensitization to SH was absent in all subjects. The percent of subjects with positive SPTs to mites (p < 0.01), pollen (p < 0.01) and molds (p < 0.05) were higher in subjects with a positive SPT to SH versus those with a negative SPT to SH. Sixty-six percent of subjects with DE and 13.6% of subjects with IE or UE reported respiratory symptoms after SD inhalation (Odds Ratio: 12.67 [2.4-74.9], p < 0.001). Compared to subjects exclusively sensitized to mites, patients sensitized to SH presented significantly different clinical characteristics. Soybean production has been increasing in Argentina during the last 20 years, determining an increase in the population exposed to chronic SD inhalation. This fact determines a high risk of sensitization and triggering of respiratory symptoms in atopic subjects. This study demonstrates that there is: 1) a high prevalence of skin reactivity to SH in subjects with asthma and/or allergic rhinitis from Argentina and that this prevalence is associated with the level of exposure to SD, and 2) an association between sensitivity to SH and severity of asthma. Measures to avoid release and inhalation of SD in rural areas from Argentina are needed.

Asociación entre exposición a polvo de soja, sensibilidad alérgica y perfil de síntomas respiratorios / [Association between soybean dust exposure, allergic sensitivity and profile of respiratory symptoms]

The purpose of this study was to correlate soybean dust (SD) exposure, skin reactivity to soybean hull (SH) allergens, and symptoms of asthma and/or allergic rhinitis. A group of 365 subjects with asthma and/or allergic rhinitis and a control group of 50 individuals without respiratory symptoms were studied. The level of exposure to SD is defined as follows: 1) direct (DE); 2) indirect (ID), and 3) urban (UE). All subjects completed standard questionnaires. Skin tests with a SH extract and with common allergens were performed by the prick technique (SPT). Fifty-six (15.3

) patients and no subjects from control group had positive SPT (histamine index > or = 0.5) with a SH allergen extract. The percentages of positive SPT to SH extract were 38.7

in subjects with DE, IE and UE, respectively (p < 0.001). Monosensitization to SH was absent in all subjects. The percent of subjects with positive SPTs to mites (p < 0.01), pollen (p < 0.01) and molds (p < 0.05) were higher in subjects with a positive SPT to SH versus those with a negative SPT to SH. Sixty-six percent of subjects with DE and 13.6

of subjects with IE or UE reported respiratory symptoms after SD inhalation (Odds Ratio: 12.67 [2.4-74.9], p < 0.001). Compared to subjects exclusively sensitized to mites, patients sensitized to SH presented significantly different clinical characteristics. Soybean production has been increasing in Argentina during the last 20 years, determining an increase in the population exposed to chronic SD inhalation. This fact determines a high risk of sensitization and triggering of respiratory symptoms in atopic subjects. This study demonstrates that there is: 1) a high prevalence of skin reactivity to SH in subjects with asthma and/or allergic rhinitis from Argentina and that this prevalence is associated with the level of exposure to SD, and 2) an association between sensitivity to SH and severity of asthma. Measures to avoid release and inhalation of SD in rural areas from Argentina are needed.

Asociación entre exposición a polvo de soja, sensibilidad alérgica y perfil de síntomas respiratorios. / [Association between soybean dust exposure, allergic sensitivity and profile of respiratory symptoms]

The purpose of this study was to correlate soybean dust (SD) exposure, skin reactivity to soybean hull (SH) allergens, and symptoms of asthma and/or allergic rhinitis. A group of 365 subjects with asthma and/or allergic rhinitis and a control group of 50 individuals without respiratory symptoms were studied. The level of exposure to SD is defined as follows: 1) direct (DE); 2) indirect (ID), and 3) urban (UE). All subjects completed standard questionnaires. Skin tests with a SH extract and with common allergens were performed by the prick technique (SPT). Fifty-six (15.3

) patients and no subjects from control group had positive SPT (histamine index > or = 0.5) with a SH allergen extract. The percentages of positive SPT to SH extract were 38.7

, 20.3

and 8.4

in subjects with DE, IE and UE, respectively (p < 0.001). Monosensitization to SH was absent in all subjects. The percent of subjects with positive SPTs to mites (p < 0.01), pollen (p < 0.01) and molds (p < 0.05) were higher in subjects with a positive SPT to SH versus those with a negative SPT to SH. Sixty-six percent of subjects with DE and 13.6

of subjects with IE or UE reported respiratory symptoms after SD inhalation (Odds Ratio: 12.67 [2.4-74.9], p < 0.001). Compared to subjects exclusively sensitized to mites, patients sensitized to SH presented significantly different clinical characteristics. Soybean production has been increasing in Argentina during the last 20 years, determining an increase in the population exposed to chronic SD inhalation. This fact determines a high risk of sensitization and triggering of respiratory symptoms in atopic subjects. This study demonstrates that there is: 1) a high prevalence of skin reactivity to SH in subjects with asthma and/or allergic rhinitis from Argentina and that this prevalence is associated with the level of exposure to SD, and 2) an association between sensitivity to SH and severity of asthma. Measures to avoid release and inhalation of SD in rural areas from Argentina are needed.

Evidence that antisulfatide autoantibodies from rats experimentally infected with Trypanosoma cruzi bind to homologous neural tissue.

Earlier studies in Trypanosoma cruzi-infected rats revealed an increased antibody activity against sulfatide, a specific constituent of both myelin sheaths of peripheral nerves and T. cruzi epimastigotes. To investigate further the characteristics of such anti-sulfatide antibodies, we analyzed their IgG isotypes as well as their ability to bind to homologous neural host structures. Antisulfatide IgG-enriched fractions were obtained from rats acutely infected with T. cruzi. Immunoglobulin isotypes were determined by an enzyme-linked immunosorbent assay (ELISA) method to show that IgG2a and, more significantly, IgG2b were the predominant isotypes of antisulfatide autoantibodies. Further immunofluorescence studies carried out in coronal sections of the rat forebrain revealed, in turn, that antisulfatide antibodies were capable of reacting with homologous neural tissues. Specific binding of these rat autoantibodies to sulfocerebroside on cell surfaces in vivo may in theory play some detrimental role, given the reported ability of rat IgG2b to fix complement or to mediate antibody-dependent cell-mediated cytotoxicity reactions.

Prevalencia de sensibilización a lepidoglyphus destructor, tyrophagus putrescentiae y chortoglyphus arcuatus en pacientes con asma y/o rinitis residentes en Rosario / Prevalence of sensitization to lepidoglyphus destructor, tyrophagus putrescentiae and chortoglyphus arcuatus in patients with asthma and/or rhinitis living in Rosario, Argentine

El objetivo del presente trabajo fue evaluar la prevalencia de la sensibilización a Lepidoglyphus destructor (Ld), Tyrophagus putrescentiae (Tp) y Chortoglyphus arcuatus (Cha) en pacientes con asma y/o rinitis que residen exclusivamente en Rosario y compararla con otros ácaros estudiados previamente. En tres centros privados y tres hospitales públicos, se estudiaron 216 pacientes, 54,6 por ciento de sexo femenino, con edades comprendidas entre los 5 y 55 años (x 23,3 años). El 20,8 por ciento de ellos presentaba asma, el 38,9 por ciento rinitis y el 40,3 por ciento ambas patologías. Se confeccionó un cuestionario tipo y se realizaron prick tests (SPT) con extractos de Ld, Tp, Cha, Dermatophagoides pteronsyssinus (Dp) y Blomia tropicalis (Bt) obtenidos a partir de aislamiento y cultivos locales, y con una batería de aeroalergenos comerciales. El 79,6 por ciento (n = 172) de los pacientes presentó al menos un STP (+) y de ellos, el 94,8 por ciento mostró sensibilidad a algún ácaro y el 48,3 por ciento a otros alergenos. La prevalencia de sensibilización a alguno de los tres ácaros en estudio fue de 76,2 por ciento (Ld 69,2 por ciento, Cha 64,0 por ciento y Tp 61,6 por ciento), siendo de 66,1 por ciento en los pacientes con rinitis, de 78,9 por ciento en asma y de 82,7 por ciento para ambas patologías. No se observaron diferencias entre centros públicos y privados. El 54,6 por ciento de los pacientes (n=89) tuvo SPT (+) para los 5 ácaros testeados, el 6 por ciento (n=13) fue (-) para Dp y (+) para alguno de los otros 4 ácaros y el 3 por ciento (n=6) fue (+) sólo a Ld, Tp ó Cha. Se concluye que la prevalencia de sensibilización a Ld, Tp y Cha hallada en Rosario justifica ampliamente su inclusión en el panel de aeroalergenos, lo que permitiría identificar sensibilizaciones inaparentes

Prevalencia de sensibilización a lepidoglyphus destructor, tyrophagus putrescentiae y chortoglyphus arcuatus en pacientes con asma y/o rinitis residentes en Rosario / Prevalence of sensitization to lepidoglyphus destructor, tyrophagus putrescentiae and chortoglyphus arcuatus in patients with asthma and/or rhinitis living in Rosario, Argentine

El objetivo del presente trabajo fue evaluar la prevalencia de la sensibilización a Lepidoglyphus destructor (Ld), Tyrophagus putrescentiae (Tp) y Chortoglyphus arcuatus (Cha) en pacientes con asma y/o rinitis que residen exclusivamente en Rosario y compararla con otros ácaros estudiados previamente. En tres centros privados y tres hospitales públicos, se estudiaron 216 pacientes, 54,6 por ciento de sexo femenino, con edades comprendidas entre los 5 y 55 años (x 23,3 años). El 20,8 por ciento de ellos presentaba asma, el 38,9 por ciento rinitis y el 40,3 por ciento ambas patologías. Se confeccionó un cuestionario tipo y se realizaron prick tests (SPT) con extractos de Ld, Tp, Cha, Dermatophagoides pteronsyssinus (Dp) y Blomia tropicalis (Bt) obtenidos a partir de aislamiento y cultivos locales, y con una batería de aeroalergenos comerciales. El 79,6 por ciento (n = 172) de los pacientes presentó al menos un STP (+) y de ellos, el 94,8 por ciento mostró sensibilidad a algún ácaro y el 48,3 por ciento a otros alergenos. La prevalencia de sensibilización a alguno de los tres ácaros en estudio fue de 76,2 por ciento (Ld 69,2 por ciento, Cha 64,0 por ciento y Tp 61,6 por ciento), siendo de 66,1 por ciento en los pacientes con rinitis, de 78,9 por ciento en asma y de 82,7 por ciento para ambas patologías. No se observaron diferencias entre centros públicos y privados. El 54,6 por ciento de los pacientes (n=89) tuvo SPT (+) para los 5 ácaros testeados, el 6 por ciento (n=13) fue (-) para Dp y (+) para alguno de los otros 4 ácaros y el 3 por ciento (n=6) fue (+) sólo a Ld, Tp ó Cha. Se concluye que la prevalencia de sensibilización a Ld, Tp y Cha hallada en Rosario justifica ampliamente su inclusión en el panel de aeroalergenos, lo que permitiría identificar sensibilizaciones inaparentes (AU)

Depressed autoantibody synthesis in Trypanosoma cruzi-infected rats born to mothers undergoing this infection during pregnancy.

Earlier work indicated that Trypanosoma cruzi infection in pregnant rats decreased the amount of myocardial damage that developed in their chronically infected offspring. Given the suspected role of autoimmune mechanisms in the generation of chronic myocarditis, we evaluated whether this maternal intervention was likely to affect the synthesis of autoantibodies in infected young. Autoantibodies were investigated against molecules exhibiting cross-reactivity with T. cruzi antigens or not, that is cerebroside sulphate (sulphatide) and actin, respectively. Female '1' rats (75 days old) that had been mated with syngeneic sires were separated into two groups, one challenged with living trypomastigotes at 7, 14 and 21 days following mating, and the other one given physiologic saline at the same intervals. At the time of weaning, offspring were injected with 10(6)/T. cruzi to constitute two infected groups: young born to infected mothers (InMoTc) and young delivered by uninfected mothers (CoMoTc). Serum antibodies were investigated by ELISA at 30 and 60 days post-infection, which represents acute and chronic infection, respectively. T. cruzi infection was associated with the production of anti-sulphatide antibodies, but the phenomenon was significantly less evident in InMoTc young and virtually unnoticeable during their chronic infection. Unlike the anti-sulphatide results, levels of anti-actin antibodies showed no differences between CoMoTc and InMoTc rats when compared during acute or chronic infection. The decreased production of anti-sulphatide autoantibodies of InMoTc offspring may be due to a modification of the immune repertoire of offspring because of the contact with parasite antigens during ontogeny.

Inhibition of trypomastigotes' infectivity by a monoclonal antibody directed to a glycoconjugated fraction of epimastigotes of Trypanosoma cruzi.

In this work it was shown that the infectivity of trypomastigote forms of Trypanosoma cruzi was affected upon the interaction with the Monoclonal Antibody (McAb) 2E9, which was raised against a glycoconjugated fraction of membranes of epimastigotes (Tulahuen strain). Characterization of the epitope recognized by this McAb, as well as its effects on complement mediated lysis and host cell invasion are reported. Immunocytochemical analysis showed that the McAb was reactive with two macromolecules (41-58 kDa) present on Trypanosoma cruzi epimastigotes (Tulahuen and Y strain), while it recognized several trypomastigotes macromolecules, showing a more intense reactivity with a band of 80 kDa. By indirect immunofluorescence, it was found there were subpopulations of blood and tissue culture derived trypomastigotes which attach the antibody to varying degrees. Studies using chemical or enzymatically treated antigens suggested that the McAb 2E9 was directed against carbohydrate epitopes, which were identified as being--galactosyl residues. In addition, preliminary results are shown, suggesting that the epitope recognized by the McAb 2E9 is involved in adhesion/or internalization of trypomastigotes.

Epitope contiguous chains and antibody recognition in HIV-1 synthetic peptide antigens.

Five peptides derived from human immuno deficiency virus (HIV-1) gp41 transmembrane protein have been synthesized: M9 (610-618), M12 (598-609), M15 (600-614), M21 (584-604) and M23 (587-609). These sequences partially overlap in the region vicinal to the immunodominant epitope CSGKLIC, between two cysteine residues 603-609 and three of them (M12, M15 and M23) include this complete heptapeptide. M23, the longer peptide, includes an hydrophilic chain in addition to the heptapeptide loop. The purpose of this work was to determine the influence of contiguous chains to the heptapeptide loop on antibody recognition in fluid and solid phases, and dissociation constants (KD) of each sequence with human anti-HIV-1 antibodies. Two peptides, M13 and M23, overlapped on this loop, were found to be more reactive. Antigen-antibody dissociation constants were determined for both peptides by competition enzyme-linked immunosorbent assay, using each peptide alternatively as the solid phase-immobilized antigen. In addition to the influence of solid-phase antigen on calculated dissociation constants (a phenomenon described by Seligman, 1994), the inhibitory effect of M15 in liquid phase on antibody binding to solid phase M23 was higher than exerted by M23 in solution over antibody binding to M15 on solid phase. On the basis of peptide sequence and predicted antigenicity, this behavior appeared to be contradictory. It is assured that the possible origin of this phenomenon is due to unfavorable conformation of the longer peptide. Even though synthetic peptides mimic mainly sequential epitopes, conformational preferences in fluid or solid phase play an important role in epitope functionality. In particular, addition of residues to known immunodominant sequences may not always amplify antibody recognition if conformation provokes steric hindrance in the native epitope.

Prevalencia de sensibilización a Blomia tropicalis en Rosario: estudio multicéntrico / The prevalence of the sensitivity to Blomia tropicalis in Rosario city: multicenters studies

Se evaluó la prevalencia de la sensibilización a Blomia tropicalis en pacientes con asma y/o rinitis que residen exclusivamente en la ciudad de Rosario,para valorar si existen diferencias entre la respuesta cutánea a cuerpo total y a partículas fecales y relacionar la misma con diferentes parámetros clínicos y de laboratorio. Se estudiaron 314 pacientes, 164 femeninos (52,2 por ciento) con edades entre 5 a 55 años (x 20,8 DS ñ 13,7). 87 pacientes presentaban solamente asma, 91 solamente rinitis y 136 ambas patologías. El estudio se realizó en 8 centros asistenciales de la ciudad de Rosario, 3 públicos y 5 privados, completando todos un cuestionario tipo y realizando la misma técnica de testificación con un extracto de idéntico origen (División de Alergia e Inmunología, University of South Florida, Tampa, U.S.A.). Se llevó a cabo prick test (SPT) a una concentración de 1/50 p/v de cuerpo total (ECT) de Blomia tropicalis y de partículas fecales (EPF) de la misma, comparando la pápula obtenida con cada extracto con la de la histamina y se consideró positivo un índice de histamina > 0,5. Además, cada centro, realizó SPT con una batería de aeroalergenos, considerando como positiva una pápula mayor de 5 mm. Se obtuvo un total de 280 (89,2 por ciento) pruebas cutáneas positivas para al menos un aeroalergenos. De los 314 individuos estudiados 224 (71,3 por ciento) resultaron positivos para el extracto de cuerpo total de B. tropicalis y 207 (66 por ciento) para el extracto de partículas fecales. Veinte (7,1 por ciento) de los 280 SPT "+" respondieron exclusivamente a Blomia tropicalis. La prevalencia de sensibilización a Dermatophagoides pteronyssinus y/o Dermatophagoides farinae fue del 76,1 por ciento (239 pacientes) y la de otros neumoalergenos del 38,5 por ciento (121 pacientes). Confirmando un reporte previo, la prevalencia de sensibilización a Blomia tropicalis posee una relevancia casi tan importante como la de los ácaros Pyroglyphidos en la ciudad de Rosario. El análisis comparativo mostró que la sensibilidad a Blomia tropicalis es significativamente mayor en el grupo etario de 10 a 20 años (x²= 11,1 p<0,01), en los pacientes con una IgE total > 300 kU/l (x²=33,5 p<0,001) y en los pacientes con asma y rinitis (x²=14,4 p<0,001). Fué también significativa la diferencia entre el tamaño de la pápula del extracto de cuerpo de Blomia tropicalis y los distintos grupos etarios (x²=28,6 p<0,001) así como en el nivel de IgE total (x²=34,9 p<0,001).

Prevalencia de sensibilización a Blomia tropicalis en Rosario: estudio multicéntrico / The prevalence of the sensitivity to Blomia tropicalis in Rosario city: multicenters studies

Se evaluó la prevalencia de la sensibilización a Blomia tropicalis en pacientes con asma y/o rinitis que residen exclusivamente en la ciudad de Rosario,para valorar si existen diferencias entre la respuesta cutánea a cuerpo total y a partículas fecales y relacionar la misma con diferentes parámetros clínicos y de laboratorio. Se estudiaron 314 pacientes, 164 femeninos (52,2 por ciento) con edades entre 5 a 55 años (x 20,8 DS ñ 13,7). 87 pacientes presentaban solamente asma, 91 solamente rinitis y 136 ambas patologías. El estudio se realizó en 8 centros asistenciales de la ciudad de Rosario, 3 públicos y 5 privados, completando todos un cuestionario tipo y realizando la misma técnica de testificación con un extracto de idéntico origen (División de Alergia e Inmunología, University of South Florida, Tampa, U.S.A.). Se llevó a cabo prick test (SPT) a una concentración de 1/50 p/v de cuerpo total (ECT) de Blomia tropicalis y de partículas fecales (EPF) de la misma, comparando la pápula obtenida con cada extracto con la de la histamina y se consideró positivo un índice de histamina > 0,5. Además, cada centro, realizó SPT con una batería de aeroalergenos, considerando como positiva una pápula mayor de 5 mm. Se obtuvo un total de 280 (89,2 por ciento) pruebas cutáneas positivas para al menos un aeroalergenos. De los 314 individuos estudiados 224 (71,3 por ciento) resultaron positivos para el extracto de cuerpo total de B. tropicalis y 207 (66 por ciento) para el extracto de partículas fecales. Veinte (7,1 por ciento) de los 280 SPT "+" respondieron exclusivamente a Blomia tropicalis. La prevalencia de sensibilización a Dermatophagoides pteronyssinus y/o Dermatophagoides farinae fue del 76,1 por ciento (239 pacientes) y la de otros neumoalergenos del 38,5 por ciento (121 pacientes). Confirmando un reporte previo, la prevalencia de sensibilización a Blomia tropicalis posee una relevancia casi tan importante como la de los ácaros Pyroglyphidos en la ciudad de Rosario. El análisis comparativo mostró que la sensibilidad a Blomia tropicalis es significativamente mayor en el grupo etario de 10 a 20 años (x²= 11,1 p<0,01), en los pacientes con una IgE total > 300 kU/l (x²=33,5 p<0,001) y en los pacientes con asma y rinitis (x²=14,4 p<0,001). Fué también significativa la diferencia entre el tamaño de la pápula del extracto de cuerpo de Blomia tropicalis y los distintos grupos etarios (x²=28,6 p<0,001) así como en el nivel de IgE total (x²=34,9 p<0,001). (AU)

Anticarsia gemmatalis nuclear polyhedrosis virus replication in serum-free and serum-reduced insect cell cultures.

In order to develop a financially feasible process to produce Anticarsia gemmatalis Nuclear Polyhedrosis virus in cell culture, we developed a lipidic supplement to replace fetal calf serum in insect cell culture media. The supplement, prepared with an extract of lipids from hen egg yolk, allowed us to reduce the contents of serum in the culture medium from 10% to 1%. IPLB-Sf-21 cells could be kept along consecutive passages in serum-reduced medium. The replication of AgNPV in HEYLE-supplemented cultures was evaluated. Extracellular virions production was the same as in FCS-supplemented-cultures, but the production level of polyhedral inclusion bodies was significantly lowered in HEYLE-supplemented cultures. The reduced production of PIBs is related to a premature releasing of non-occluded particles as well as to a reduced synthesis of polyhedrin protein.

Rapid determination of Trypanosoma cruzi urinary antigens in human chronic Chagas disease by agglutination test.

Detection of Trypanosoma cruzi in man becomes particularly difficult during the chronic stage of Chagas disease because of the low parasitemia. We were able to develop a simple and straightforward method for determining the concentration of T. cruzi antigens in urine using nitrocellulose micellar suspension (Nitrocell-Mr, Polychaco Argentina) and for their subsequent detection through a "latex" type agglutination test. The latex used was an esferocell nitrocellulose suspension (Esferocell-Mr, Polychaco). Specific antigens for T. cruzi were detected in 54 of 58 urine samples from chronic chagasic patients. The antigens characterized by affinity chromatography and SDS-PAGE were glycoproteins with apparent molecular weights (and pIs) of 100 kDa (pI 5 to 5.5), 80 kDa (pI 6.0), and 50 kDa (pI 6.5 to 7.0). This method is practical and fulfills the requirement of large-scale epidemiological studies. It is also helpful in cases of conflictive serology.

Expression of protozoan antigens by hybrids between Leishmania mexicana and myeloma SP2/0.

Hybrid cells were obtained between Leishmania mexicana promastigotes and mouse myeloma SP2/0 cells, and examined for expression of leishmanial antigens. A ratio of 1:10 of myeloma to T. cruzi cells was unsuccessful because of outgrowth of non-fused cells. With a ratio of 2:1 four waves of multiplication of 'chimeric' cells were observed over 45 days. The death of the hybrids after this period is explained by segregation of DNA and loss of chromosome material. Hybrid cells gave a positive reaction with antibodies in the sera from patients infected with Leishmania, as demonstrated by indirect immunofluorescence. Conversely, promastigote forms of Leishmania gave a negative reaction with the same antibodies, which recognize surface antigens of the amastigote stage of Leishmania. It is possible therefore that amastigote stage antigens are expressed on the surface of the 'chimeric' hybrid as a result of transformation of promastigotes following hybridization.

Peanut agglutinin affinity chromatography of Trypanosoma cruzi glycoproteins.

Glycoproteins from Trypanosoma cruzi epimastigotes have been extracted by diiodosalycilic acid and lithium salts, and phenol-water biphasic partition. Peanut agglutinin has been used in a one step preparative method for fractionating the total extract in order to separate the so-called galactose-terminal glycoproteins. The different fractions have been studied by SDS electrophoresis, ultracentrifugation and immunoelectrophoresis techniques. The experimental immunogenicity, antigenicity and specificity of the PNA affinity fractions has been evaluated.

Immunoenzymatic determination of antibody-bound soluble antigens ofTrypanosoma cruzi.

Anti-Major Cathodic Antigen (MCA) monospecific immunoglobulins ofT. cruzi have been used for the preparation of polyamide-linked immunoadsorbents. A high proportion of serologically positive patients with Chagas disease show the presence of a soluble antigen complexed with human immunoglobulins, which complex binds to those immunoadsorbents as determined by a double sandwich reaction and a peroxidase final determination.