Serum antibodies blocked by glycan antigens in canine visceral leishmaniasis serology are mostly IgA immune complexes.

Immune complexes (ICs) are found in canine visceral leishmaniasis (CVL) and interfere with the serum detection of antibodies. Dissociation of these monovalent complexes by dissociative enzyme-linked immunosorbent assay (ELISA) removes false-negative results and allows some characterization of antibodies and antigens. We studied the serology of dogs with suspected CVL in an endemic area, testing two Leishmania (Leishmania) [L. (L.)] infantum antigens. We analysed the presence of immunoglobulin G (IgG), immunoglobulin A (IgA) and immunoglobulin M (IgM) antibodies specific to promastigote soluble extract (PSE) and low-molecular weight glycans (glycan­bovine serum albumin (BSA) complex ­ GBC) by conventional and dissociative ELISA. Our results showed a significant fraction of IgA ICs (46.5% for PSE and 47.6% for GBC), followed by IgG ICs (10% for PSE and 23.5% for GBC). IgM ICs were more frequent for PSE (22.7%). Hypergammaglobulinaemia in CVL would be related to the presence of IgA and IgG ICs, resulting in deficient elimination of these antibodies. Our data confirmed the presence of ICs that can generate false-negative results in conventional serology. The production of IgA antibodies and the high frequency of blockade by glycan antigens suggest the active participation of this immunoglobulin and its ICs in the immunopathology of CVL, indicating a new path for further research.

Frequency of anti-Toxoplasma gondii antibodies in women attended at public health center network of São Paulo metropolitan region (2001-2005) / Frequência de anticorpos anti-Toxoplasma gondii em mulheres, atendidas nas unidades da rede de saúde publica da região metropolitana de São Paulo (2001-2005)

Toxoplasma gondii is an obligatory intracellular parasite that can infect man and homoeothermic animals. In immunocompetent individuals the infection is generally asymptomatic, the foremost groups seriously affected by the infection are the immunocompromised and the pregnant women who acquire the infection during pregnancy. In this survey were analyzed 1485 serum samples from women attended at public health network of São Paulo metropolitan region during the period of January 2001 to July 2005. The detection of IgG antibody anti-T.gondii was realized by enzyme-linked immunosorbent assay (ELISA), both IgG and IgM antibodies were detected by immunofluorescent antibody technique (IFAT). Among the samples analyzed 57.10% presented IgG antibody anti-T. gondii and IgM antibody was detected in 1.95% individuals. Previous epidemiologic studies performed in Brazil demonstrated an IgG antiT. gondii antibody seroprevalence varying from 40% to 80%, which corroborate with the date of the present investigation. There is the necessity of the studies to estimate the T. gondii infection prevalence rate in several Brazilian regions, in order to establish a developing health education strategies, and information programs for population to decreased congenital infection risk.

Toxoplasma gondii é um parasita intracelular obrigatório que pode infectar o homem e animais homeotérmicos. Nos indivíduos imunocompetentes a infecção é geralmente assintomática, os principais grupos atingidos gravemente pela doença são os indivíduos imunodeprimidos e as gestantes que adquirem a infecção durante a gestação. Neste trabalho foram analisadas 1485 amostras de soros de mulheres atendidas na rede pública de saúde da grande São Paulo, durante o período de janeiro de 2001 a julho de 2005. A detecção de anticorpos IgG anti-T.gondii foi realizada por meio de ensaio imunoenzimático (ELISA) e a técnica Imunofluorescência Indireta (IFAT) foi utilizada para detecção de anticorpos IgM e IgG anti- T.gondii. Das amostras analisadas 57,10% apresentaram anticorpos IgG anti-T.gondii, e 1,95% possuíam anticorpos específicos da classe IgM. Os inquéritos epidemiológicos realizados no Brasil demonstraram que a a soroprevalência de anticorpos IgG anti-T. gondii varia de 40 a 80%, o que corroboram com os dados obtidos no presente estudo. Existe a necessidade de estudos que identifiquem as taxas de prevalência nas várias regiões brasileiras, com o intuito de implantar trabalhos de informação e conscientização da população para diminuição do risco de infecção congênita por T. gondii.