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Biomedical subjects

S Giorgio

Publications and source records attributed to S Giorgio.

7 recordsLinked to original sources
PubMed1993

Trypanosoma cruzi: antibody production and T cell response induced by stage-specific surface glycoproteins purified from metacyclic trypomastigotes.

The main surface glycoproteins of metacyclic trypomastigotes of Trypanosoma cruzi, gp90, gp82, and gp35/50, were purified and the immune response elicited by these antigens was analyzed. Balb/c mice immunized with antibody-affinity-purified gp82, plus alum as adjuvant, produced antibodies that recognized both the gp82 and the heterologous gp90 and gp35/50. On the other hand, antisera to gp90 reacted only with the homologous antigen, either by immunoprecipitation or by immunoblotting. Neither sera reacted with unrelated proteins in ELISA. Both antisera lysed 90-100% metacyclic forms in a complement-mediated reaction, a property associated with protection. However, in contrast to gp90, previously shown to induce protective immunity against acute T. cruzi infection, gp82 was not immunoprotective. Lymph node (LN) cells of mice primed with gp82 or gp90, which display 40% amino acid sequence identity at the carboxy terminal domain, were strongly stimulated in vitro by either one of these antigens. Proliferation, inhibitable by anti-CD4 but not by anti-CD8 antibodies, was T. cruzi-specific, no activation being observed with irrelevant antigens. LN cells of mice immunized with unrelated proteins did not proliferate in vitro in the presence of gp82 or gp90. The 35/50-kDa glycoconjugate, which was phenol-extracted, did not elicit any detectable antibody or T cell response.

Amino Acid Sequence↗
PubMed1993

Glycosphingolipid antigens of Leishmania (Leishmania) amazonensis amastigotes identified by use of a monoclonal antibody.

Monoclonal antibodies directed against Leishmania (Leishmania) amazonensis amastigotes were produced. One monoclonal antibody (1C3) selected by indirect immunofluorescence reacted with both amastigotes and promastigotes of L. (L.) amazonensis. Glycolipid extraction from L. (L.) amazonensis amastigotes and separation by high-performance thin-layer chromatography followed by immunoblotting demonstrated that 1C3 reacts with two glycosphingolipids which migrate chromatographically similarly to ceramide-N-acetylneuraminic acid (GM1) and ceramide-N-tetrose-di-acetylneuraminic acid (GD1a). The antibody did not react with glycosphingolipids from L. (L.) amazonensis promastigotes. Immunoprecipitation of 125I- and 35S-methionine-labeled promastigotes demonstrated that 1C3 recognizes gp63 from L. (L.) amazonensis promastigotes. Biosynthetic incorporation of labeled lipids by L. (L.) amazonensis amastigotes indicated that the glycosphingolipids reactive with 1C3 contain oleic acid in their structures. Surface labeling with galactose oxidase and sodium boro[3H]hydride indicated that galactose is present in 1C3-reactive antigens, strongly suggesting that these glycosphingolipids are localized on the surface of L. (L.) amazonensis amastigotes. Inhibition experiments of macrophage infection implicated the 1C3-reactive glycosphingolipids from L. (L.) amazonensis amastigotes in Leishmania invasion. The role of gp63 in promastigote-macrophage attachment was also demonstrated by inhibition experiments performed with 1C3, consistent with data from the literature.

Animals↗
PubMed1992

Inhibition of mouse lymphocyte proliferative response by glycosphingolipids from Leishmania (L.) amazonensis.

The effect of a purified preparation of glycosphingolipids (GSLs) extracted from Leishmania (L.) amazonensis amastigotes on murine lymphocytes was investigated. GSLs inhibited both concanavalin A (Con A)- or lipopolysaccharide-induced [3H]thymidine uptake by normal and immunized BALB/c mouse lymph node cells. The effect of total GSLs was dose dependent. Total GSLs also suppressed the two-way mixed lymphocyte reaction of BALB/c x C57BL/6 cells and the antigen-specific response of immunized mouse cells. Six pure bands as well as a pool containing a mixture of GSLs with five to seven sugar residues separated by a combination of HPLC and preparative HPTLC were tested and shown to be inhibitors of Con A stimulation. These results suggest that parasite glycosphingolipids may play an immunologically relevant role in leishmaniasis.

Animals↗
PubMed1990

Identification of T-cell reactive antigens in Nippostrongylus brasiliensis using a cell immunoblotting technique.

Antigens of the nematode Nippostrongylus brasiliensis were fractionated by SDS-PAGE under reducing conditions, transferred electrophoretically onto nitrocellulose and converted to antigen-bound nitrocellulose particles for use in in vitro proliferation assays. Mesenteric lymph node cells from infected rats were analyzed for reactivity against the fractionated antigens, revealing a range of different molecular weight antigens. In addition, when supernatants from these cultures were assayed for IL3, further reactive antigens were detected. The results demonstrated that these approaches are useful for the identification of T-cell reactive components of a complex mixture of parasite antigens in helminth infections, where the cellular nature of protection is not well defined.

Animals↗
PubMed1986

Number of chromosomes, Feulgen-DNA content, and nuclear phenotypes in domestic and wild specimens of Panstrongylus megistus.

Specimens of Panstrongylus megistus with different levels of adaptation to a domestic way of life had some of their nuclear and chromosomal characteristics compared, in an attempt to differentiate them by cytological means. The number of chromosomes in male testes was found not to differ. The nuclear frequency and phenotypes of the Malpighian tubules were also found to be the same. On the other hand, Feulgen-DNA values of metaphase chromosomes in insects from a population with a sylvatic distribution were found to be larger than those in specimens from a domestic population. The differences in Feulgen-DNA values, however, may not represent real differences in DNA content, but may possibly be due to differences in DNA-protein complexes.

Analysis of Variance↗