INTRODUÇÃO: A síndrome antifosfolípide (SAF) é uma condição autoimune que apresenta fenômenos trombóticos arteriais e venosos de repetição além de complicações obstétricas. Sua patogênese está associada à presença de anticorpos antifosfolípides e/ou anti-β2 glicoproteína I (β2GPI) que aparentemente modificam o efeito anticoagulante da β2GPI. A dimerização da β2GPI induzida por anticorpos parece estar relacionada à indução da agregação plaquetária contribuindo para o estado trombofílico na SAF. OBJETIVOS: O presente trabalho objetiva demonstrar a influencia dos anticorpos antifosfolípides em testes de agregação plaquetária com diferentes agonistas (ADP, colágeno e adrenalina). MÉTODOS: Foram analisados testes de agregação de plaquetas normais com diferentes agonistas (ADP, colágeno, adrenalina) na presença de soro contendo anticorpos antifosfolípides em diferentes concentrações. RESULTADOS: As análises obtidas mostraram uma inibição significativa (P < 0,05) nas curvas de agregação plaquetária induzidas por ADP e adrenalina quando comparadas ao controle. O paradoxo entre o estado protrombótico e a presença de autoanticorpos que in vitro apresentam atividade anticoagulante foi demonstrado na literatura, dificultando o entendimento patofisiológico da síndrome antifosfolípide. CONCLUSÃO: Os resultados obtidos demonstraram que o soro rico em anticorpos anticardiolipina e anti-β2GPI, ambas da classe IgG, interferem em testes de curvas de agregação plaquetária.

INTRODUCTION: The antiphospholipid syndrome (APS) is an autoimmune condition characterized by recurrent arterial and venous thrombosis, besides obstetric complications. The pathogenesis is associated with the presence of antiphospholipid and/or anti-b2-glicoprotein I (anti-b2GPI) antibodies that appear to change the anticoagulant activity of b2GPI. Antibody-induced dimerization of b2GPI seems to be related to the induction of platelet aggregation, contributing to the development of thrombosis in APS. OBJECTIVES: The objective of the present study is to demonstrate the influence of antiphospholipid antibodies in platelet aggregation tests with different agonists (ADP, collagen, and adrenaline). METHODS: We analyzed platelet aggregation tests with different agonists (ADP, collagen, adrenalin) when normal platelets were exposed to serum with different concentrations of antiphospholipid antibodies. RESULTS: Results demonstrated a significant inhibition in adrenalin- and ADP-induced platelet aggregation curves (P < 0.05) in all antibody concentrations tested when compared to the control. The paradox between the prothrombotic state and the presence of autoantibodies that show anticoagulant activity in vitro was demonstrated in the literature, making it difficult to understand the pathophysiologic mechanism of the antiphospholipid syndrome. CONCLUSION: Results showed that anticardiolipin and anti-b2GPI antibodies-rich serum, both of which belonging to the IgG class, can interfere with platelet aggregation curves.

INTRODUCTION: Hantavirus is a genus of ribonucleic acid (RNA) viruses included in the family Bunyaviridae. Hantaviruses are rodent-borne zoonoses that, in the last 18 years, became an emergent public health problem in the Americas, causing a severe cardiopulmonary syndrome. This disease has no specific treatment and has a high case fatality. The transmission of hantavirus to man occurs by inhaling aerosols of rodent excreta. The aim of this study was to determine the prevalence of antibodies to hantavirus in the population of the rural settlement of Tupã in the county of Marcelândia, state of Mato Grosso, Brazil. METHODS: The participants of the serologic survey were visited at their homes and selected randomly among the settlement population. Blood samples of the participants were collected by venopuncture. The serum samples were tested by an IgG-ELISA using an N recombinant protein of Araraquara hantavirus as antigen, using the protocol previously established by Figueiredo et al. RESULTS: IgG antibodies to hantavirus were detected in 7 (13%) of the 54 participants. The positivity was higher among men. It was observed that there was an association of seropositivity to hantavirus within the participants born in the south of Brazil. CONCLUSIONS: The results suggest that, in this rural area, everyone is exposed to the same risk of becoming infected with hantavirus, and, therefore, there is a need to intensify surveillance activities and education of the local people to prevent this viral infection.

OBJETIVO: Esse estudo tem o objetivo de avaliar a frequência dos HPAs em pacientes onco-hematológicos trombocitopênicos e analisar a probabilidade de incompatibilidade associada à transfusão de plaquetas. MÉTODOS: A genotipagem plaquetária foi realizada para os alelos HPA-1a, HPA-1b; HPA-2a, HPA-2b; HPA-3a, HPA-3b; HPA-4a, HPA-4b; HPA-5a, HPA-5b; HPA-15a, HPA-15b por PCR-SSP em 150 pacientes atendidos pelo Serviço de Hematologia do Hospital das Clínicas da FMUSP. RESULTADOS: As frequências alélicas encontradas foram: HPA-1a: 0,837; HPA-1b: 0,163; HPA-2a: 0,830; HPA-2b: 0,170; HPA-3a: 0,700; HPA-3b: 0,300; HPA-4a: 1; HPA-4b: 0; HPA-5a: 0,887; HPA-5b: 0,113; HPA-15a: 0,457; HPA-15b: 0,543. CONCLUSÃO: A análise dos HPAs neste estudo demonstrou que os alelos A são mais frequentes na população do que os alelos B, com exceção do HPA-15, sugerindo que pacientes homozigotos para os alelos B apresentam maior predisposição à aloimunização e refratariedade às transfusões de plaquetas por causa imune. A genotipagem plaquetária pode ser de grande valia para o diagnóstico de trombocitopenia aloimune e para prover concentrados de plaquetas compatíveis a esses pacientes.

OBJECTIVE: The objective of this study was to evaluate the frequencies of human platelet antigens in oncohematological patients with thrombocytopenia and to analyze the probability of their incompatibility with platelet transfusions. METHODS: Platelet antigen genotyping was performed by sequence-specific primer polymerase chain reaction (SSP-PCR) for the HPA-1a, HPA-1b, HPA-2a, HPA-2b, HPA-3a, HPA-3b, HPA-4a, HPA-4b, HPA-5a, HPA-5b; HPA-15a, HPA-15b alleles in 150 patients of the Hematology Service of the Hospital das Clínicas (FMUSP). RESULTS: The allele frequencies found were: HPA-1a: 0.837; HPA-1b: 0.163; HPA-2a: 0.830; HPA-2b: 0.170; HPA-3a: 0.700; HPA-3b: 0.300; HPA-4a: 1; HPA-4b: 0; HPA-5a: 0.887; HPA-5b: 0.113; HPA-15a: 0.457 and HPA-15b: 0.543. CONCLUSIONS: Data from the present study showed that the A allele is more common in the population than the B allele, except for HPA-15. This suggests that patients homozygous for the B allele are more predisposed to present alloimmunization and refractoriness to platelet transfusions by immune causes. Platelet genotyping could be of great value in the diagnosis of alloimmune thrombocytopenia and to provide compatible platelet concentrates for these patients.