Distinct cytokine profiles of circulating mononuclear cells stimulated with Staphylococcus aureus enterotoxin A in vitro during early and late episodes of chronic osteomyelitis

We investigated the cytokine profile of peripheral mononuclear cells from chronic osteomyelitis (OST) patients following in vitro stimulation with staphylococcal enterotoxin A (SEA). We demonstrate that stimulation with SEA induced prominent lymphocyte proliferation and high levels of tumour necrosis factor (TNF)-α, interleukin (IL)-4 and IL-10 secretion in both OST and non-infected individuals (NI). Even though stimulation with SEA had no impact on IL-6 production in either patient group, the baseline level of IL-6 production by cells from OST patients was always significantly less than that produced by cells from NI. After classifying the osteomyelitic episodes based on the time after the last reactivation event as "early" (1-4 months) or "late" osteomyelitis (5-12 months), we found that increased levels of TNF-α and IL-4 in combination with decreased levels of IL-6 were observed in the early episodes. By contrast, increased levels of IL-10, IL-2 and IL-6 were hallmarks of late episodes. Our data demonstrate that early osteomyelitic episodes are accompanied by an increased frequency of "high producers" of TNF-α and IL-4, whereas late events are characterised by increased frequencies of "high producers" of IL-10, IL-6 and IL-2. These findings demonstrate the distinct cytokine profiles in chronic osteomyelitis, with a distinct regulation of IL-6 production during early and late episodes.

Diagnosing human asymptomatic visceral leishmaniasis in an urban area of the State of Minas Gerais, using serological and molecular biology techniques

A population-based cross-sectional study was set up in Sabará country, Southeastern Brazil, to identify asymptomatic human visceral leishmaniasis in an urban area of low disease prevalence. Blood was collected on filter paper (n=1,604 inhabitants) and examined by indirect immunofluorescent test, enzyme-linked immunosorbent assay and immunochromatographic strip test. The prevalence rates of infection ranged from 2.4 to 5.6 percent depending on the test used. One year later, venous blood was collected in a subset of 226 participants (102 seropositive and 124 seronegative). The tests performed were IFAT, ELISA, rk39-ELISA, polymerase chain reaction and hybridization with Leishmania donovani complex probe. No clinical signs or symptoms of leishmaniasis were observed. Using hybridization as a reference test, the sensitivity and specificity of serology were respectively: 24.8 and 71 percent (ELISA); 26.3 and 76.3 percent (rk-39); 30.1 and 63.4 percent (IFAT). Due to disagreements, different criteria were tested to define the infection and hybridization should be considered in epidemiological studies.

Um estudo seccional de base populacional foi desenvolvido no município de Sabará, região sudeste do Brasil, para identificar a leishmaniose visceral humana assintomática em uma área urbana de baixa prevalência da doença. Foi coletado sangue em papel filtro (n=1.604 moradores), sendo examinados pela reação de imunofluoresência indireta, ensaio imunoenzimático e teste imunocromatográfico (strip test). As taxas de prevalência da infecção variaram de 2,4 a 5,6 por cento, dependendo do teste utilizado. Um ano depois foi coletado sangue venoso de um subgrupo de 226 participantes (102 soropositivos e 124 soronegativos). Os testes realizados foram IFAT, ELISA, rk39-ELISA, reação em cadeia da polimerase e hibridização com sonda específica para o complexo Leishmania donovani. Não foi observado nenhum sinal clínico ou sintoma de leishmaniose. Usando a hibridização como teste de referência, a sensibilidade e especificidade dos testes sorológicos foram, respectivamente: 24.8 e 71 por cento (ELISA); 26,3 e 76,3 por cento (rk39-ELISA); 30,1 e 63,4 por cento (IFAT). Devido a discordâncias, diferentes critérios foram testados para definir a presença da infecção e a hibridização deveria ser considerada em estudos epidemiológicos.