Human serum antibody reactivity towards Paracoccidioides brasiliensis antigens treated with sodium metaperiodate.

In this study, we evaluated the profile of anti-Paracoccidioides brasiliensis immunoglobulin isotypes in serum from patients with the acute and chronic forms of paracoccidioidomycosis, using the whole Paracoccidioides brasiliensis antigen and the antigen treated with sodium metaperiodate. All the immunoglobulin isotypes present in the serum from patients with the acute and chronic forms of paracoccidioidomycosis presented higher reactivity towards the whole antigen than to the antigen treated with metaperiodate (P < 0.05). The reactivity of IgG and IgM to the antigen treated with metaperiodate was greater in serum from patients with the acute form of the disease (P < 0.05), while IgA was more reactive in serum from patients with the chronic form (P < 0.05). There was greater reactivity of IgG1 and IgG2 to the whole antigen and the antigen treated with metaperiodate in the serum from patients with paracoccidioidomycosis than there was in serum from patients with other parasitic infections (P < 0.05). Furthermore, IgG1 from patients with the acute form recognized the 19kDa, 27kDa and 31kDa antigens in the western blot test. Thus, the results suggest that modifications to the epitopes of Paracoccidioides brasiliensis antigens may help to improve the immunodiagnosis of paracoccidioidomycosis.

Human serum antibody reactivity towards Paracoccidioides brasiliensis antigens treated with sodium metaperiodate / Reatividade de anticorpos de soros humanos a antígenos de Paracoccidioides brasiliensis tratados com metaperiodato sódico

In this study, we evaluated the profile of anti-Paracoccidioides brasiliensis immunoglobulin isotypes in serum from patients with the acute and chronic forms of paracoccidioidomycosis, using the whole Paracoccidioides brasiliensis antigen and the antigen treated with sodium metaperiodate. All the immunoglobulin isotypes present in the serum from patients with the acute and chronic forms of paracoccidioidomycosis presented higher reactivity towards the whole antigen than to the antigen treated with metaperiodate (P < 0.05). The reactivity of IgG and IgM to the antigen treated with metaperiodate was greater in serum from patients with the acute form of the disease (P < 0.05), while IgA was more reactive in serum from patients with the chronic form (P < 0.05). There was greater reactivity of IgG1 and IgG2 to the whole antigen and the antigen treated with metaperiodate in the serum from patients with paracoccidioidomycosis than there was in serum from patients with other parasitic infections (P < 0.05). Furthermore, IgG1 from patients with the acute form recognized the 19kDa, 27kDa and 31kDa antigens in the western blot test. Thus, the results suggest that modifications to the epitopes of Paracoccidioides brasiliensis antigens may help to improve the immunodiagnosis of paracoccidioidomycosis.

Neste trabalho, foi avaliado o perfil de isotipos de imunoglobulinas anti-Paracoccidioides brasiliensis em soros de pacientes com formas crônica e aguda de paracoccidiodomicoses usando antígeno total e tratado com meta-periodato. Todos os tipos de imunoglobulinas presentes nos soros de pacientes com formas aguda e crônica apresentaram alta reatividade ao antígeno total quando comparado ao tratado com meta-periodato (P < 0,05). Houve maior reatividade de IgG e IgM anti-antígeno tratado com meta-periodato em soros de pacientes com forma aguda da doença (P < 0,05), enquanto IgA foi mais reativa em soros da forma crônica (P < 0,05). Houve maior reatividade de IgG1 e IgG2 com antígeno total e tratado com meta-periodato em soros de pacientes comparados aos com outras parasitoses (P < 0,05). Além disso, IgG1 de pacientes com a forma aguda reconhecem antígenos de 19kDa, 27kDa e 31kDa por western blot. Assim, os resultados sugerem que alterações nos epitopos de antígenos de Paracoccidioides brasiliensis podem auxiliar no aprimoramento do imunodiagnóstico da paracoccidioidomicose.

Complex gangliosides affect GD3 accessibility to antibody in developing neuronal cells.

Ganglioside expression of embryonic chick retina cells developed in vitro was analyzed by indirect immunofluorescence. Immature neurons were GD3 positive cells and the labeling was chiefly distributed all over their cell membrane. Mature neurons became GD3 negative and expressed complex gangliosides of the a- and b-pathways; nevertheless, the content of GD3 accounted for approximately 40% of the total gangliosides in these cells. Neuraminidase hydrolysis pointed out that GD3 was located in membrane of differentiated cells. The frequency of cells with the GD3 immunostain localized in restricted area of membrane of undifferentiated neurons increased significantly after adding a mixture of bovine brain gangliosides (largely complex gangliosides). Antibody binding to immobilized GD3 showed a dose-dependent inhibition by adding a mixture of bovine brain gangliosides, GM1, GD1a or asialo-GM1. Glycosphingolipids with shorter oligosaccharide chains, as cerebrosides or sulfatides, did not affect this binding. These results suggest that, concomitant with the accretion of content of complex gangliosides, a rearrangement in the membrane would occur, which progressively masks GD3 to its antibody. This rearrangement might affect putative ganglioside functions involved in neuronal differentiation.

Chemically unrelated mycobacterial peptides as antigens and competitors in antigen recognition by human T cells.

Understanding resistance to mycobacterial infectious diseases requires identification of antigens and epitopes (antigenic determinants) that stimulate cell-mediated immune responses. In this study, a DR1-restricted T cell epitope (residues 1 through 20) of the 19-kD protein of M. tuberculosis was identified. Peripheral blood mononuclear cells from two HLA-DR1 patients with tuberculosis responded not only to the 19-kD immunoblot fraction of M. tuberculosis but also to the peptide 1-20. A M. tuberculosis-reactive T cell clone isolated from one of the patient (whose mononuclear cells showed a stronger proliferative response to the 19-kD protein) recognized the peptide 1-20, while failed to recognize a negative control peptide (residues 65 through 85 of the 65-kD mycobacterial protein: peptide 65-85) or a negative control antigen (candida). The antigen recognition to peptide 1-20 was shown to be DR1 restricted. This MHC restriction was confirmed using a DR1-restricted mycobacterial T cell epitope as competitor. These results demonstrated that this mycobacterial competitor significantly reduced the antigen recognition of peptide 1-20. The reduction observed was dose-dependent.

Comparison of clinical and experimental data from an animal model of pulmonary immunologic sensitivity.

Isocyanates are highly reactive chemicals capable of causing a multitude of toxicologic effects including respiratory irritation, dermal irritation, contact sensitivity, and pulmonary hypersensitivity. In order to probe the mechanism(s) underlying these reactions, an animal model has been developed. The guinea pig model reproduces both the respiratory and immunologic effects of isocyanates that have been observed clinically. In experimental animals and in humans, isocyanates induce immunologic reactions with specific antibody formation, including IgE. This finding allows development of diagnostic reagents to assess isocyanate sensitivity. Further characterization of immunologic components in the model is expected to increase understanding of the mechanisms of this immunotoxic disease and develop strategies for treatment and prevention.

Lytic, agglutinating, and opsonizing effect of alpha 2-macroglobulin on sheep red blood cells.

Mouse alpha 2-macroglobulin (alpha 2M) induced agglutination and lysis of sheep red blood cells depending on temperature and time of incubation in vitro. When these erythrocytes (E) were treated with a subagglutinanting dose of alpha 2M, they were adhered to and phagocytosed by thioglycollate-elicited and BCG-activated mouse peritoneal macrophages. Phagocytosis was not observed when resident peritoneal macrophages were tested. alpha 2M also was able to dissociate sheep red blood cells previously aggregated by IgM anti-E.

Inflamación / Inflamation

En este estudio se resaltan algunos de los avances más importantes la amplia información que cada día pone en evidencia la magnitud de la respuesta denominada inflamación, la cual está asociada a reacciones inmunes. La alteración farmacológica de la acción que ejercen los mediadores de la inflamación es punto importante en la terapéutica de estas enfermedades