Dose-dependent systemic human immunodeficiency virus infection of SCID-hu mice after intraperitoneal virus injection

SCID mice were engrafted with human foetal liver, thymus and lung. Human cells were subsequently detected among peripheral blood leukocytes for 81% of tested animals and in tissue implants for 100% of tested animals. SCID-hu mice received intraperitoneal injections of human immunodeficiency virus type 1 (HIV1) at from 20 up to 20,000 median tissue culture infectious doses (TCID5). HIV1 infection was detected by means of cell culture and polymerase chain reaction both in blood and implants, up to 58 days after infection. The rate of infection was dependent upon the inoculated dose: the frequency of thymus infection ranged from 14% with 20-500 TCID50 up to 100% with 20,000 TCID50. HIV1 infection was detected less frequently in blood leukocytes than in thymus. Thymus virus load ranged from 40 to 50,000 HIV1 provirus copies per million cells and was not correlated with either infectious dose or viraemia. Thymus T-cell depletion was observed mainly in the CD1+4+8+ immature thymocyte compartment. The same rate of SCID-hu mouse infection was obtained using three different primary HIV1 isolates, suggesting that infection was not restricted to a few particular virus strains. The systemic infection of SCID-hu mice following intraperitoneal virus injection mimics some traits of human HIV infection and provides a promising, novel approach for future investigations in this field.

Human IgE in SCID mice reconstituted with peripheral blood mononuclear cells from Dermatophagoides pteronyssinus-sensitive patients

SCID mice were reconstituted with purified peripheral blood mononuclear cells from patients sensitive to Dermatophagoides pteronyssinus (Dpt). After immunization with a low dose of the related allergen, these human (Hu)-SCID mice may develop a specific IgE response. By using an IgE-dependent platelet assay and the related allergen Dpt, the human IgE was demonstrated to be functional. Indeed a high correlation was obtained between both parameters. No rise in human IgE level was detected within 3 wk after the immunization with an unrelated Ag. When mice were reconstituted with peripheral blood cells from nonallergic donors and immunized with the Dpt allergen, no human IgE production was evidenced in the serum of SCID mice. However, in both allergic Hu-SCID mice (reconstituted with cells from allergic patients) or in nonallergic Hu-SCID mice (reconstituted with cells from healthy donors), an IgG response was detectable. Finally by radioallergosorbent test, a specific IgE Ab response was detected after the first allergen challenge only in allergic Hu-SCID mice. Thus, without ethical constraints, SCID mice represent a useful model for analyzing the IgE response occurring in allergic patients.

Human IgE in SCID mice reconstituted with peripheral blood mononuclear cells from Dermatophagoides pteronyssinus-sensitive patients

SCID mice were reconstituted with purified peripheral blood mononuclear cells from patients sensitive to Dermatophagoides pteronyssinus (Dpt). After immunization with a low dose of the related allergen, these human (Hu)-SCID mice may develop a specific IgE response. By using an IgE-dependent platelet assay and the related allergen Dpt, the human IgE was demonstrated to be functional. Indeed a high correlation was obtained between both parameters. No rise in human IgE level was detected within 3 wk after the immunization with an unrelated Ag. When mice were reconstituted with peripheral blood cells from nonallergic donors and immunized with the Dpt allergen, no human IgE production was evidenced in the serum of SCID mice. However, in both allergic Hu-SCID mice (reconstituted with cells from allergic patients) or in nonallergic Hu-SCID mice (reconstituted with cells from healthy donors), an IgG response was detectable. Finally by radioallergosorbent test, a specific IgE Ab response was detected after the first allergen challenge only in allergic Hu-SCID mice. Thus, without ethical constraints, SCID mice represent a useful model for analyzing the IgE response occurring in allergic patients.

Synovial fibroblast-like cell transfection with the SV40 large T antigen induces a transformed phenotype and permits transient tumor formation in immunodeficient mice

OBJECTIVE

To understand the intracellular signals leading to transformed-like growth of synovial fibroblast-like cells from patients with rheumatoid arthritis (RA).

METHODS

Cell lines stably transfected with one or both of 2 complementary oncogenes, the SV40 large T antigen and the ras oncogene, were studied for phenotypic changes.

RESULTS

Synovial fibroblast-like cells stably transfected with the SV40 large T antigen, but not the ras oncogene, showed high levels of growth factor independent proliferation, grew under anchorage independent conditions, expressed cathepsin L mRNA, and formed transient tumors in immunodeficient mice. Synovial fibroblast-like cells stably transfected with both oncogenes appeared phenotypically similar to synovial fibroblast-like cells transfected with the large T antigen alone.

CONCLUSION

The SV40 large T antigen confers a phenotype on synovial fibroblast-like cells similar to that stimulated by growth factors, suggesting that it stimulates the same intracellular signalling pathway leading to cytokine induced, transformed synovial fibroblast-like cell growth. When injected into immunodeficient mice these transfected cells formed tumors characterized by rapid, transient growth, central necrosis, and neutrophil infiltration.

SCID-Hu mouse as a model for human lung HIV-1 infection

HIV induces a multi-organ infection with a dual tropism for both lymphocytes and monocytes/macrophages. The lung is a target both for HIV infection and HIV-related opportunistic infections. The SCID mouse has provided the opportunity to develop a small animal model for HIV infection. However, HIV-1 infection of the human fetal thymus and liver (SCID Liv/Thy) implanted in these mice occurred only after direct intraimplant injection of HIV-1 and the resultant HIV-1 infection was restricted to the human thymus. Here we report that human foetal lung can develop in SCID Liv/Thy mice resulting in the development of normal human alveolar and bronchiolar lung compartments which can be productively infected with cell-free HIV-1 virus, leading to a systemic and bifocal infection. This SCID-Hu model should be useful for studying AIDS physiopathology, human viruses with lung tropism and for helping to define gene therapy protocols in lung human cells in vivo.

[Sensitivity and specificity of antineutrophil cytoplasmic antibodies in systemic vasculitis]

The diagnostic value of c-ANCA as a specific marker of systemic vasculitis (particularly Wegener's granulomatosis) is well established. The prognostic value of c-ANCA for determining disease activity is controversial. We have prospectively studied in ten patients with systemic vasculitis over a mean period of 34 months (extreme 2-61 months). All patients had c-ANCA at the moment of the diagnosis: four patients had high titer of c-ANCA all over the period study; three clinical and biological exacerbations of the disease was observed without variation of the c-ANCA titer. In four patients c-ANCA disappeared within 6 months after the beginning of the treatment correlated with disease activity. Sometimes a rise of c-ANCA titer was observed with or without disease activity. In one case c-ANCA titer had a serrated evolution. The sensitivity and the specificity of the c-ANCA for disease activity in the ten studied patients were respectively 1 and 0.28. In patients with systemic vasculitis and c-ANCA at the time of the diagnosis, variation in c-ANCA titer alone is of limited prognostic value for predicting disease course.

High osmotic pressure for Pneumocystis carinii London Resin White embedding enables fine immunocytochemistry studies: I. Golgi complex and cell-wall synthesis

A method for embedding Pneumocystis carinii in hydrophilic resin (London Resin White) has been developed for immunocytochemistry studies. Using high osmotic pressure (about 850 mosmol) from fixation to embedding, this method improved the preservation of the fine structure as well as the antigenicity of rabbit- and SCID mouse-derived P. carinii. Cytochemistry studies were performed using colloidal gold-conjugated lectins (concanavalin A, glycine max, Ulex europaeus) that reacted with the cytoplasmic components (endoplasmic reticulum, Golgi vesicles). Colloidal gold-conjugated streptavidin was also tested and was found to be reactive with the parasite cell wall and cytoplasmic components, which precludes its indiscriminate use in P. carinii immunocytochemistry studies.

Introduction of Pneumocystis carinii in a colony of SCID mice

Pneumocystis carinii-free SCID mice were housed closely exposed to corticosteroid-treated non-SCID mice in a conventional area of our laboratory animal facilities. A one-day exposure was sufficient for P. carinii transmission. The lung infection increased thereafter. Irradiation or splenectomy of SCID mice at the beginning of the exposure resulted in a marked increase of parasite multiplication. Extrapulmonary foci of pneumocystosis were detected in heart and spleen of SCID mice infected by P. carinii via air transmission.

Obtention of a human primary humoral response against schistosome protective antigens in severe combined immunodeficiency mice after the transfer of human peripheral blood mononuclear cells

Peripheral blood mononuclear cells (PBMC) from healthy donors were injected into C.B.-17 severe combined immunodeficiency (scid) mice which were subsequently immunized with crude Schistosoma mansoni adult worm antigenic preparation (SWAP) or with recombinant S. mansoni 28-kDa glutathione transferase (r-Sm-28-GST) antigen. PBMC from a S. mansoni-infected patient were also transferred. The specific human anti-SWAP and anti-Sm-28-GST antibody responses were monitored. The presence in both cases of human specific antibodies in scid mouse sera was determined by enzyme-linked immunosorbent assay and Western blotting techniques using anti-human immunoglobulin reagents. No antibodies were detected in these sera using anti-mouse immunoglobulin antisera. These antibodies were functional since a cytotoxic activity against schistosomula was observed when monocytes were incubated with scid mouse sera positive for anti-Sm-28-GST antibodies.

Hymenolepis diminuta: intestinal mast cell and eosinophil response of the mouse to infection

It has been demonstrated that the rejection of Hymenolepis diminuta by the mouse is characterized by a humoral response in serum and intestinal lavage. Now the response is also shown to be accompanied by a mast cell and eosinophil response in the lamina propria of the intestine. The mast cell response is, in time and place, correlated with the rejection process of H. diminuta. With regard to the number of eosinophils in the lamina propria, a significant response was only found in the second half of the intestine. The eosinophil peroxidase (EPO) concentration in the intestinal lumen is correlated with the rejection of the parasite and illustrates the involvement of eosinophils in the rejection process. The course of the EPO response is identical to the mast cell response. This, together with other results, suggests that, as to other "systemic" worm infections, a mast cell-eosinophil response may be, at least in part, responsible for the rejection of H. diminuta from the intestinal lumen.

Molecular characterization of a 23-kilodalton major antigen secreted by Toxoplasma gondii

The strategy chosen for cloning potential vaccine antigens of Toxoplasma gondii was based on the hypothesis that the definitive protection observed in natural infection is due to the presence of encysted bradyzoite forms in host tissues throughout life. The antigens released by the bradyzoites would maintain an immune response against the invading tachyzoites. This led us to identify in tachyzoite in vitro translation products a polypeptide of 24 kDa that is an excreted-secreted antigen (ESA) and is cross-reactive with bradyzoites. In addition, the detection of anti-P24 IgG antibodies is correlated with the chronic infection in man. The gene encoding P24 has been isolated, sequenced, and expressed in Escherichia coli and eukaryotic cells. The recombinant proteins were immunogenic in mice, producing anti-native P23 antibodies. Immunocytochemical analysis located the native antigen in the dense granules of both tachyzoite and bradyzoite forms and showed that it is secreted within host-cell-modified phagosome. Moreover 45Ca2+ labeling as well as regional homologies indicate that this protein has Ca2+-binding properties, suggesting its physiological importance in host-cell invasion. P23 is of diagnostic interest as a marker of chronic toxoplasmosis and is proposed as a vaccine component.

Isolation and in vitro translation of Onchocerca volvulus mRNA

Adult Onchocerca volvulus recovered for excised nodules by dissection or treatment with collagenase have been used as a source of RNA for in vitro translation experiments. RNA was purified using either the hot phenol/SDS procedure or the guanidine isothiocyanate protocol. Immunoprecipitation experiments performed on in vitro products demonstrate a marked heterogeneity in responses by individed human infection sera. Further immunoprecipitation experiments demonstrate cross reactivity between O. volvulus and other filarial nematodes.

Brugia malayi microfilariae share epitopes with Aedes aegypti

Shared antigens between Brugia malayi and Aedes aegypti were studied. The experiments carried out with sera from infected Mastomys natalensis indicated that an immunological response against A. aegypti antigens (Mr 185, 35, 32 kDa) appeared often when animals became microfilaraemic and increased progressively in intensity during the time-course of infection. Sera of animals immunized with B. malayi reacted with the crude extract of mosquitoes and conversely, antibodies from animals immunized with A. aegypti reacted with the surface of B. malayi microfilariae. The implications of these findings of the natural history of B. malayi infection are discussed.

Onchocerca volvulus. Monoclonal anti-idiotype antibody as antigen signal for the microfilaricidal cytotoxicity of diethylcarbamazine-treated platelets

Over the past 35 yr, diethylcarbamazine (DEC) has been the most widely used agent for the treatment of filarial diseases, particularly in onchocerciasis. The microfilaricidal action of DEC has been recently shown to be mediated by blood platelets with the additional triggering of a filarial excretory Ag (FEA). This FEA could be detected by using mAb in the serum of infected patients. By using one mAb (IA2(23] directed against Onchocerca volvulus and recognizing circulating Ag (Ab1), we purified by affinity chromatography the target molecule of IA2(23) (an O. volvulus glycoprotein recognized by IA2(23) mAb). This compound had a dose-dependent effect on the cytotoxic action of DEC-treated platelets. We subsequently produced an anti-idiotype mAb to Ab1 (Ab2), and considered the possibility of replacing the O. volvulus glycoprotein recognized by IA2(23) mAb by Ab2. Ab2 was selected according to its ability to inhibit the binding of radioiodinated Ab1 to the filarial target Ag. It induced the production of anti-O. volvulus antibodies (Ab3) in rats. At a constant concentration of DEC platelets, the addition of increasing amounts of Ab2 led to a dose-dependent cytotoxic effect against parasite larvae. Experiments performed with Ab2 on detergent solubilized surface proteins of platelets identified four bands of Mr 18, 26, 43.5, and 100 kDa, supporting the idea of the presence of binding sites on the platelets for a FEA required for the microfilaricidal cytotoxicity of DEC-treated platelets.

Onchocerca volvulus. Monoclonal anti-idiotype antibody as antigen signal for the microfilaricidal cytotoxicity of diethylcarbamazine-treated platelets

Over the past 35 yr, diethylcarbamazine (DEC) has been the most widely used agent for the treatment of filarial diseases, particularly in onchocerciasis. The microfilaricidal action of DEC has been recently shown to be mediated by blood platelets with the additional triggering of a filarial excretory Ag (FEA). This FEA could be detected by using mAb in the serum of infected patients. By using one mAb (IA2(23] directed against Onchocerca volvulus and recognizing circulating Ag (Ab1), we purified by affinity chromatography the target molecule of IA2(23) (an O. volvulus glycoprotein recognized by IA2(23) mAb). This compound had a dose-dependent effect on the cytotoxic action of DEC-treated platelets. We subsequently produced an anti-idiotype mAb to Ab1 (Ab2), and considered the possibility of replacing the O. volvulus glycoprotein recognized by IA2(23) mAb by Ab2. Ab2 was selected according to its ability to inhibit the binding of radioiodinated Ab1 to the filarial target Ag. It induced the production of anti-O. volvulus antibodies (Ab3) in rats. At a constant concentration of DEC platelets, the addition of increasing amounts of Ab2 led to a dose-dependent cytotoxic effect against parasite larvae. Experiments performed with Ab2 on detergent solubilized surface proteins of platelets identified four bands of Mr 18, 26, 43.5, and 100 kDa, supporting the idea of the presence of binding sites on the platelets for a FEA required for the microfilaricidal cytotoxicity of DEC-treated platelets.

Lymphatic filariasis: detection of circulating and urinary antigen and differences in antibody isotypes complexed with circulating antigen between symptomatic and asymptomatic subjects

A two-site immunoradiometric assay using a monoclonal antibody (MoAb) against Brugia malayi microfilariae allowed the detection of parasite molecules both in the serum and the urine of patients from Sri Lanka infected with Wuchereria bancrofti. Whereas 50% of patients had no antigen in their serum, all of them excreted detectable amounts of antigen in their urine, the levels being higher in symptomatic than in asymptomatic patients. The poor detection in serum appeared to be related to the presence of circulating immune complexes. It was shown that the isotype of the antibodies complexed with the circulating antigen was IgM in the asymptomatic group, while it was mainly IgG in the symptomatic patients (swelling and lymphoedema or elephantiasis). These results suggest the existence of regulatory immune mechanisms affecting the clinical expression of lymphatic filariasis.

IgE-dependent killing of Schistosoma mansoni schistosomula by human platelets: modulation by T cell products

The in vitro stimulation of T lymphocytes is known to induce the release of factors that possess distinct biological activities. In the present report, we describe the presence, in supernatants of Schistosoma mansoni antigen stimulated T cells from S. mansoni infected patients, of a factor able to inhibit the IgE-dependent platelet cytotoxicity of the same individuals toward the young larvae of S. mansoni.

IgE-dependent killing of Brugia malayi microfilariae by human platelets and its modulation by T cell products

Platelets isolated from patients infected with filariasis were cytotoxic for microfilariae in vitro. Moreover, platelets from normal donors acquired killing properties in the presence of serum from infected individuals. The humoral factor involved in this cytotoxic process was shown to be IgE. This IgE-dependent cytotoxicity of platelets was strongly inhibited by antigen-stimulated T lymphocyte supernatants from filarial patients.

Influence of an Hymenolepis diminuta infection on IgE and IgA bound to mouse intestinal eosinophils

Infection of mice with Hymenolepis diminuta, which is an 'exclusively' intestinal cestode, affects the number of eosinophils and non-eosinophilic cells with IgE or IgA on their surface in the lamina propria. Presence of IgE on eosinophils is basically a primary infection response, while after reinfection the response is primarily characterized by IgA. For IgE- as well as for IgA-bearing eosinophils the response is most abundant in the second quarter of the intestine which is the parasite's preferred habitat. For non-eosinophilic cells the effect is smaller and limited to the IgE-bearing cells, with the most significant effect in the second quarter of the intestine.

Platelets mediate the action of diethylcarbamazine on microfilariae

More than 400 million people in the world are infected by filarial parasites leading to a wide range of pathologies. Although introduced in 1947, the mainstay of the therapy and control of the filariases is diethylcarbamazine (N,N-diethyl-4-methyl-1-piperazine carboxamide; DEC), the mode of action of which still remains unknown despite widespread use and intensive laboratory investigations. The marked contrast between an extremely rapid action in vivo and the absence of any significant activity on microfilariae in vitro is unique among chemotherapeutic agents. DEC has been thought to modify the surface layer of the microfilariae and expose them to immunological cell-mediated lysis. This report provides the first evidence that the effect of DEC is mediated by blood platelets with the additional triggering of a filarial excretory antigen (FEA). The killing mechanism is antibody-independent and involves the participation of free radicals.

Detection of circulating and urinary antigens in Mastomys natalensis experimentally infected with Brugia malayi, Brugia pahangi, or Litomosoides carinii

The time-course of the detection of circulating and urinary filarial antigens was followed with a 2S-IRMA assay, using a mouse monoclonal antibody raised against Brugia malayi larvae, in Mastomys natalensis experimentally infected with Brugia malayi, Brugia pahangi, or Litomosoides carinii. In the prepatent phase of the infections, filarial antigen was detected 4-7 weeks before microfilariae appeared in the peripheral blood. Moreover, the sensitivity of the test was greater with urine than with serum. During the patent phase of infection, the level of circulating antigens detected varied considerably. However, there was a positive correlation (P less than 0.05) between antigenemia and microfilaremia. In L. carinii infection, filarial antigen could be easily detected in spite of the disappearance of microfilariae in peripheral blood, 49 weeks post infection. If these results are extrapolated to man, the 2S-IRMA should be useful for epidemiological surveys in endemic areas where transmission has been eliminated.

Role of specific IgE antibodies in peroxidase (EPO) release from human eosinophils

After the demonstration of cytophilic IgE immunoglobulins (Ig) on human blood and lung eosinophils, their role in cell activation was studied by eosinophil peroxidase (EPO) assay. Hypodense human eosinophils from filariasis-infected patients were activated by anti-human Ig or various antigens. A selective release of EPO occurred after incubation with anti-human IgE, but not with anti-human IgG. The activation by antigens showed a strict antibody specificity of cytophilic IgE antibodies. The direct involvement of IgE antibodies in activation by the specific antigen was evidenced by inhibition experiments with aggregated human IgE myeloma protein. Circulating IgE antibodies exhibiting the same specificity and able to induce EPO release were detected in the sera from filariasis patients by a passive sensitization assay. Only the hypodense eosinophils were able to release EPO after IgE-dependent activation both in the direct assay and in the passive sensitization test, confirming the functional heterogeneity of human eosinophils. These results suggest that the interaction between IgE antibodies and human eosinophils can play a role both in protective immunity and pathology by releasing active pharmacologic mediators.

Role of specific IgE antibodies in peroxidase (EPO) release from human eosinophils

After the demonstration of cytophilic IgE immunoglobulins (Ig) on human blood and lung eosinophils, their role in cell activation was studied by eosinophil peroxidase (EPO) assay. Hypodense human eosinophils from filariasis-infected patients were activated by anti-human Ig or various antigens. A selective release of EPO occurred after incubation with anti-human IgE, but not with anti-human IgG. The activation by antigens showed a strict antibody specificity of cytophilic IgE antibodies. The direct involvement of IgE antibodies in activation by the specific antigen was evidenced by inhibition experiments with aggregated human IgE myeloma protein. Circulating IgE antibodies exhibiting the same specificity and able to induce EPO release were detected in the sera from filariasis patients by a passive sensitization assay. Only the hypodense eosinophils were able to release EPO after IgE-dependent activation both in the direct assay and in the passive sensitization test, confirming the functional heterogeneity of human eosinophils. These results suggest that the interaction between IgE antibodies and human eosinophils can play a role both in protective immunity and pathology by releasing active pharmacologic mediators.