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The present study investigated the expression of the complement receptor type 1 (CR1) on the membrane of erythrocytes (CR1/E) of patients with systemic lupus erythematosus (SLE) by flow cytometry. We found a significant reduction in CR1/E numbers in SLE patients (n = 52), compared to controls (512 +/- 171 and 689 +/- 146, respectively, P = 0.0001). Reduction was more pronounced in active disease patients. The mean CR1/E number observed in patients with inactive disease was 546 +/- 163 CR1/E, while active SLE patients presented a mean of 385 +/- 133 CR1/E (P = 0.001). Patients with SLE with similar activity indexes tend to have similar CR1/E numbers, irrespective of disease severity. We also observed a trend to CR1/E reduction in severe nephritis patients. A small group of SLE patients with chronic renal failure and inactive disease showed CR1/E numbers nearly identical to controls (689 +/- 146 versus 686 +/- 123, respectively, P = 0.95). This was the only group of SLE patients with normal CR1/E numbers. These results confirm the CR1/E reduction in SLE patients as previously described, and also suggest that this reduction is related to disease activity and not to disease severity.

In order to investigate further the adaptive response of moulds to ambient pH, we have measured by ELISA the pho-2-encoded Pi-repressible alkaline phosphatase synthesised by Neurospora crassa. We showed that the 74A and pho-2A strains of this mould secrete similar amounts of the pho-2-encoded enzyme irrespective of ambient pH, when both the preg and pgov genes are not functional, i.e., in strains nuc-2 + growing under Pistarvation. This suggests that pho-2, which is responsive to Pi starvation via the action of genes nuc-2, preg, pgov and nuc-1, is not a gene responsive to ambient pH and that the differential glycosylation observed for the Pi-repressible alkaline phosphatase retained by the mycelium at pH 5.6 or secreted into the growth medium at pH 8.0 is the genetic response to ambient pH sensing in N. crassa.

Summary. In order to understand the mechanism of complement (C) activation by immune complexes (ICs), the anti-complementary effect of ICs containing cationized antigens was compared in vitro to that using ICs formed by native antigens. ICs were prepared with affinity-purified rabbit polyclonal IgG antibovine serum albumin (BSA) antibody and either native BSA (isoelectric point 4.2) or BSA rendered cationic by treatment with ethylenediamine (isoelectric point 9.4). Native and cationized antigens were characterized by isoelectric focusing. ICs containing anti-BSA IgG or F(ab H ) 2 , formed either at equivalence or in excess of native or cationized antigen, were submitted to ultracentrifugation in a sucrose gradient for mesh size determination. The anti-complementary effect of ICs was evaluated by kinetic determination of haemolytic activity of human serum on haemolysinsensitized sheep red blood cells. In conditions of antigen excess, the ICs formed by cationized BSA were significantly more efficient in activating human complement than those formed by native antigen. This higher activity was dependent on cationized antigen complexed with complete antibody molecules, as non-complexed cationized BSA or ICs prepared with F(ab H ) 2 fragments were inactive under the same experimental conditions. Furthermore, this difference did not depend on the mesh size of the immune Correspondence: Luciana Simon Pereira Crott, Departamento de Ana  lises Clõ Ânicas, Toxicolo  gicas e Bromatolo  gicas,

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RESUMO: A tipagem molecular do genoma bacteriano, na maioria das vezes, envolve a análise de fragmentos de restrição do DNA cromossômico. Desde que a ribotipagem foi descrita, em 1986, tem sido amplamente utilizada para analisar relações taxonômicas e/ou epidemiológicas entre os diferentes grupos de organismos. A ribotipagem usa o padrão de restrição do opéron de RNA ribossômico (rrn) como ferramenta epidemiológica e tem fornecido ótimos resultados para a detecção de polimorfismo do comprimento dos fragmentos de restrição (RFLPs). O número de opérons rrn da bactéria está diretamente relacionado ao potencial discriminatório da técnica, fornecendo um maior ou menor número de bandas. UNITERMOS: Epidemiologia Molecular. Técnicas para Tipagem de Bactérias. Infecções Bacterianas.

The aim of our study was to investigate differences that might exist in the activation of the human complement system by F1 fractions from four different isolates of P. brasiliensis. Isolates HC and 18 (virulent), 265 (low virulence), and 9 (intermediate virulence, attenuated) were used; before the experiments, the virulence of isolates HC and 18 was recovered by in vivo passage in guinea pigs. The four isolates of the fungus were processed for purification of F1 fractions and the activation of the human complement system was studied by a kinetic method of hemolytic activity measurement. The incubation of F1 fractions in normal human serum resulted in different degrees of inhibition of the classical and alternative pathways. The F1 fraction from the low virulence isolate was more efficient than the F1 fraction from the virulent isolates (HC and 18). Previous absorption of sera with F1 fractions completely abolished classical pathway activation. Using zymosan, instead of F1, in the absorption process caused the same phenomenon, suggesting that natural or nonspecific antibodies are responsible for the classical pathway activation. The alternative pathway activation did not depend on these antibodies, but was enhanced by their presence. On the other hand, F1 fractions from virulent isolates were more active in the stimulation of neutrophil chemiluminescence compared with the F1 fraction from the low virulence isolate. Whole P. brasiliensis yeast cells (WYC) from two distinct strains, 18 and 265, showed the same patterns of response of those observed with the F1 fractions in the functions tested. These differences in the behavior of the F1 fractions as well as WYC in relation to human complement activation and consequently to neutrophil stimulation may correlate with the virulence of individual isolates and may contribute to the understanding of the inflammatory response generation and maintenance processes in paracoccidioidomycosis.

We investigated the capacity of an alkali-insoluble cell wall polysaccharide fraction (FI) ofParacoeeidioides brasiliensis to induce rat polymorphonuclear neutrophil (PMN) migratory and chemiluminescence (CL) responses. Normal rat serum pre-incubated with F1 induced a chemotactic neutrophil response which was fully abolished by heat-inactivation. The participation of the alternative complement pathway was more effective than that of the classical pathway since depletion of factor B by heating at 50°C reduced PMN migration, whereas blockade of the classical pathway with EGTA left the migratory response practically unchanged. Opsonized serum F 1 induced a significant release of oxygen radicals from PMN as measured by CL. The complement system was also found to be involved in this activity since serum inactivation at 56°C altered the CL response. In addition to complementderived fragments, other serum opsonins, probably cross-reacting antibodies, were required for optimal interaction between PM N and opsonized particles. These results contribute to the understanding of the role of fungal components and of the complement system in the inflammatory response observed in paracoccidioidomycosis.Paracoccidioidomycosis or South American blastomycosis is a deep mycosis caused by the dimorphic fungus Paracoccidioides brasiliensis and is the most widespread systemic mycosis in South America [23]. The role of phagocytic cells in the host defense against this fungus is still not well understood. The importance of polymorphonuclear neutrophils (PMN) has been suggested by the finding of a massive infiltration of these cells at the inflammatory sites during the initial stage of the disease in man [12] as well as in experimentally infected animals [3,37]. The presence of PMN has also been detected in the suppurative region of the granulomatous lesions characteristic of the chronic phase of this mycosis [4,11]. A similar inflammatory response was also observed when animals were injected with isolated components of the fungus cell wall such as lipids and polysaccharides [36,37], suggesting that these substances may play an important role in the virulence and pathogenicity of P. brasiliensis. One of these components, the alkali-insoluble polysaccharide fraction (F1),was able to induce accumulation of PMN during the early phase of the inflammatory response in experimental models [3,11]. Furthermore, the F 1 fraction was shown to be able to activate the classical and alternative complement pathways of rats both in vivo and in vitro (L. S. P. Crott, R. T. P. Sobreira, C. L. Silva & J. E. Barbosa, unpublished results).