Phagocytic cell chemiluminescence using different zymosan preparations

Avaliação da resposta imune humoral frente a antígenos de Strongyloides venezuelensis

A estrongiloidíase afeta 30 milhões de pessoas em 70 países. Usualmente, o diagnóstico dessa enteroparasitose é realizado por testes parasitológicos baseados no hidro termotropismo das larvas eliminadas nas fezes, porém esses têm se mostrado pouco sensíveis. Neste trabalho, extratos antigênicos foram testados pelas técnicas de ELISA, Immunoblotting e IFI, utilizando larvas filarióides de Strongyloides venezuelensis, parasita de roedores, que mostram reação cruzada com epítopos de Strongyloides stercoralis. Sensibilidade de 89, 85, 57% para a reação de ELISA e de 100, 100 e 96%, para o Immunoblotting com os antígenos SAL, ZWIP e ZW, e especificidade de 90, 60 e 81% para o ELISA e 96, 92 e 91% para o Immunoblotting para os mesmos antígenos, foram encontradas nestes ensaios.

Characterisation of Kupffer cells in some Amphibia

A study on the Kupffer cells (KCs) of Amphibia was undertaken in order to compare these cells with those of endothermic animals. Liver tissue and isolated and cultured KCs were studied by light microscopy and by transmission and scanning electron microscopy. We have shown that amphibian KCs can be divided into 2 principal types: 'small' and 'large'. Both cell types possess the distinctive KC morphology. They show nonspecific esterase activity, weak endogenous peroxidase activity in the nuclear envelope and in the rough endoplasmic reticulum, and the ability to engulf naturally present cell debris or experimentally administered zymosan or latex particles. The principal difference between the small and the large cells consists in the substantial quantity of inclusion bodies that exist only in the latter. We conclude that amphibian KCs, apart from their ability to build melanosomes and synthesise melanins, are very similar to mammalian KCs.

Chemiluminescent and flow cytometric analysis of gamma interferon preincubation on neonatal and adult rat polymorphonuclear leukocytes

Gamma interferon (IFN-gamma) has multiple immunomodulating effects and has been postulated as a possible immunopotentiating agent for the prevention or treatment of neonatal infections. This report describes the effect of rat recombinant IFN-gamma on the oxidative burst activity and CD11b expression of neonatal and adult rat polymorphonuclear leukocytes (PMNL). Oxidative burst activity was assessed by chemiluminescence and dihydrorhodamine flow cytometry. Neonatal PMNL exhibited significantly less oxidative burst activity than did adult PMNL. IFN-gamma mildly enhanced the chemiluminescence response of PMNL from both the rat pups and adults, but this effect was not statistically significant when analyzed by a multivariate model of repeated-measures analysis of variance for both chemiluminescence and dihydrorhodamine flow cytometry. CD11b expression was also not significantly enhanced by IFN-gamma.

The effects of endotoxin on oxygen consumption of various cell types in vitro: an EPR oximetry study

We have studied the effects of bacterial endotoxin on the oxygen consumption of a variety of target cells, and found that the rate of utilization of oxygen by treated cells was decreased in a time- and dose-dependent manner. Precise EPR measurement of oxygen concentrations enabled us to demonstrate that this effect was linked to mitochondrial dysfunction and was particular to each cell type. Such detailed knowledge on oxygen utilization by viable whole cells and the varied effects of endotoxin are as yet undocumented. Oxygen consumption was shown to decrease quite markedly in CHO cells and kidney cells from the cortex region. Cells from the kidney medulla region had lower baseline consumption and were stimulated to increased levels of oxygen consumption on addition of similar doses of endotoxin. Macrophages exhibited a dual response in that in addition to inhibiting mitochondrial oxygen consumption, endotoxin pretreatment primed these cells to exhibit an enhanced oxidative burst on stimulation with Zymosan. These results show that endotoxin has a direct effect on normal cellular oxygen consumption and is an important parameter that must be considered when following the early effects on cells and tissues during the septic syndrome.

Chemiluminescent immunoassays: discrimination between the reactivities of natural and human patient antibodies with antigens from eukaryotic pathogens, Trypanosoma cruzi and Paracoccidioides brasiliensis

Quantitative chemiluminescent enzyme-linked immunosorbent assay (ELISA) and dot-blotting procedures were developed to evaluate the reactivity of human antibodies with crude antigens and purified molecules of parasites and fungi, mainly Trypanosoma cruzi and Paracoccidioides brasiliensis. Reproducible, highly sensitive, and strictly dose-responding results were obtained, with the specificity depending on the kind of antigen used. Mixed antigens (epimastigote membrane and HIV-1 heptapeptide) applied in dots could be independently recognized by specific sera. Purified antigens (T. cruzi F2/3 and P. brasiliensis gp43) at very small concentrations gave specific reactions with patients' sera diluted > or = 1:1,000 and were very poorly reactive or unreactive with natural antibodies using the chemiluminescent immunoassays. P. brasiliensis crude antigen Fava Netto polysaccharide antigen (FNPA) contained peptide epitopes recognized by natural antibodies and carbohydrate epitopes reactive with sera from histoplasmosis patients. It is very important that sensitive chemiluminescence immunoassays be used with purified antigenic molecules to ensure specificity for the diagnosis and follow-up of parasitic and fungal infections.

Modulation of chemiluminescence in a murine macrophage cell line by neuroendocrine hormones

This study determined the effects of neuropeptides and neuroendocrine hormones at the cellular level of the immune response using a murine macrophage cell line, J774, which exhibits a chemiluminescent oxidative burst upon acute stimulation with zymosan. We report that the zymosan-triggered oxidative burst of J774 cells can be modulated by the opioid peptides beta-endorphin (beta-END) and dynorphin A (DYN) in a naloxone-reversible fashion. Norepinephrine (NE) also modulated chemiluminescence (CL) emission of J774 cells, with dose-dependent suppression of CL dependent upon co-incubation with gamma-interferon (gamma-INF). Without gamma-INF co-incubation, NE shared with the opioid peptides beta-END and DYN the ability to modulate oxidative burst, producing an inverted-U dose response. These data indicate that J774 cells may be useful for explaining some mechanisms through which the neuroendocrine system interacts with the immune system.

Effects of anti-transforming growth factor-beta antibody and interleukin-2 in tumor-bearing mice

In previous studies we found that the immunosuppression seen in mice bearing Herpes virus type 2-transformed (H238) fibrosarcoma was likely to be due to tumor-derived transforming growth factor-beta (TGF-beta). In vitro experiments showed that interleukin-2 (IL-2) and antibodies against TGF-beta could significantly counteract TGF-beta-induced depression in lymphocytes. The present study was performed to determine if the administration of polyclonal anti-TGF-beta antibody and recombinant IL-2, alone or in combination, could inhibit H238 tumor progression in vivo and to investigate possible mechanisms of action. The tumor cells were injected s.c. at 1 x 10(6) cells/mouse and treatments were given 1-10 days post-injection. In phase I, a total of 25,000 units of IL-2 (5,000 units/injection) and/or 900 ng of anti-TGF-beta (100 ng/injection) were administered i.p. per animal. Phase II was conducted similarly, except that each mouse received a total of 127,500 units of IL-2, either with or without the same amount of antibody. No treatment-related toxicity was noted. Tumor volumes were monitored for 16-18 days after tumor implantation. The H238 tumors in treated mice from both both phases grew as rapidly as, or significantly faster than, in untreated controls. Significant enhancement of tumor growth was found in the groups given IL-2 as a single agent, regardless of total dose. The combination of the higher IL-2 dose with anti-TGF-beta resulted in more rapid tumor progression than in animals given the antibody alone. Relative spleen weights, peripheral blood leukocyte counts, and the chemiluminescent oxidative burst of phagocytes were significantly elevated in all tumor-bearing mice, whereas T cell response to mitogenic stimulation was depressed. However, the oxidative burst capacity of spleen (but not blood) cells and natural killer cell cytotoxicity were markedly lower in the treated groups compared to nontreated tumor-bearing controls. In contrast, plasma levels of tumor necrosis factor-alpha and IL-2 were substantially higher in the group given both modalities (phase II) compared to the other treated groups. These findings show that anti-TGF-beta antibody, both with and without low-dose IL-2 regimens, can be safely administered in vivo. However, tumor growth was not delayed by the treatment protocols used. The induction of hyporesponsiveness in certain cell types may account, at least partly, for the enhancement seen in tumor progression.