Biomedical subjects

C Chizzolini

Publications and source records attributed to C Chizzolini.

At least 37 records · Page 2Linked to original sources

PubMed1994

Effect of pure bovine brain-derived gangliosides on normal human B cell proliferation in vitro.

Pure gangliosides obtained from bovine brain including GM1, GD1b, GT1b and asialo-GM1 (GA1) did not induce normal human B cell proliferation in vitro. No B cell proliferation was observed either when GM1 was tested in the presence of interleukin-2 (IL-2), IL-4 or IL-6. Furthermore, the proliferative responses of human B cells induced by Staphylococcus aureus Cowan I (SAC), a T cell-independent B cell mitogen, were inhibited by these gangliosides. The degree of inhibition was influenced by ganglioside-bound sialic acid, although sialic acid per se was not inhibitory. Strongest inhibition was observed in the presence of GT1b (EC50 8.8 microM/10(5) B cells) and lowest in the presence of GA1 (EC50 129.5 microM/10(5) B cells) with intermediate values for GM1 and GD1b. GM1 inhibition of SAC-induced B cell proliferation did not represent cytotoxic effects and was still evident when GM1 was added 24-48 h after the beginning of the cultures. GM1 inhibition of SAC-induced proliferation was not reversed by the addition of IL-2, IL-4, IL-6 or their combination. In addition, GM1 inhibited the ILs-driven proliferative responses of SAC-induced B cell blasts. However, no inhibition of Epstein-Barr virus-induced B cell proliferative responses was observed. In conclusion, these results show that bovine brain-derived gangliosides do not induce proliferative responses of normal human B cells but, on the contrary, inhibit B cell responses induced by SAC.

Animals↗

PubMed1993

Chagas' disease cardioneuropathy: association of anti-Trypanosoma cruzi and anti-sciatic nerve antibodies.

The aim of this work was to study whether Trypanosoma cruzi infection could elicit humoral immune response to the well-defined parasite antigen acidic fraction separated from T. cruzi cytosol by isoelectric focusing and designated fraction IV (FIV) and whether this response could account for some of the autoreactive immune response against peripheral nerve components. Chagasic patients with positive serology for Chagas' disease were classified as group I (n = 12) with normal electrocardiograms (ECG) and no signs of disease, group II (n = 12) with ECG abnormalities but without cardiomegaly, and group III (n = 12) with cardiomegaly and congestive heart failure. Sera from patients in group II showed the highest frequency of positive reactivity against FIV. Ninety-two percent had titers higher than 1/400 while the percentage for groups I and III was 50%. The autoreactive response against human sciatic nerve saline extract (SNS) was studied. The binding of IgG to SNS was positive in groups I (58%), II (66%), and III (75%) patients. The treatment of SNS with periodate diminished the ability of antigens to fix IgG from these chagasic patients. Absorption studies were performed to investigate whether FIV and SNS could have cross-reactive epitopes. Preabsorption of positive sera with FIV inhibited 48-69% of samples' reactivity against antigen. In contrast, preabsorption of positive sera with SNS inhibited only 12-23% of samples' reactivity against antigen. Overall, these results suggest that FIV-T. cruzi and sciatic nerve components possess some epitopes, possibly of a carbohydrate nature, in common. Thus, infection in Chagas' disease could overcome the tolerance to self components and could lead to autoimmunity.

Adult↗

PubMed1992

Inhibitory activity against sporozoites induced by antibodies directed against nonrepetitive regions of the circumsporozoite protein of Plasmodium vivax.

In previous studies, Saimiri sciureus boliviensis monkeys have been immunized with four recombinant proteins reproducing part of the circumsporozoite (CS) protein of Plasmodium vivax sporozoites (NS1(81) V20, rPvCS-1, rPvCS-2, rPv-CS-3), or with irradiated sporozoites of P. vivax Salvador I strain. To analyze the antibody response elicited against epitopes located outside the immunodominant repeat region of the CS protein, serum samples from these animals were tested for their ability to inhibit the in vitro development of liver stages of P. vivax VK247 strain, characterized from the other strains only by a specific repeat region on the CS protein. Results indicated that there is at least one protective B-cell epitope outside the repeat region of the CS protein of P. vivax sporozoites, and that this epitope can be expressed by irradiated sporozoites, rPvCS-1 and -3, but not by rPvCS-1 or NS1(81)V20. Therefore, we designed peptides from the amino acid sequences present both in rPvCS-2 and -3, but not included in the recombinant proteins rPvCS-1 and NS1(81)V20. Anti-peptide antibodies had no activity on the development of sporozoites of P. vivax Salvador I strain, into schizonts in primary culture of Saimiri monkey hepatocytes. In addition, antisporozoite antibodies did not react with any of the peptides. These results suggest that the in vitro inhibition observed in this study could depend upon the conformation of the CS protein. This study also demonstrates that antibody response to unnatural linear epitopes can be induced by immunization with recombinant proteins.

Amino Acid Sequence↗

PubMed1992

A monoclonal antibody directed against the sporozoite stage of Plasmodium vivax binds to liver parenchymal cells.

The circumsporozoite (CS) protein of malaria parasites is a major surface protein of the sporozoite stage. In the process of investigating the immunogenicity of this protein in the Plasmodium vivax complex, we found that a monoclonal antibody (mAb) directed against the CS protein of isolates of P. vivax recognizes New World monkey hepatocytes and human hepatoma cells HepG2A16 in Western blot and by immunoelectron microscopy. The mAb NVS3 binds to the amino acid sequence AGDR, which is also shared with the alpha 3 domain of the human and primate major histocompatibility complex class I. In addition, in vitro experiments suggest that the binding of the mAb NVS3 to hepatocytes from Saimiri monkey enhances the invasion or development of malaria sporozoites. These results form the basis for investigating the relationships between parasite surface proteins and host-cell receptors.

Amino Acid Sequence↗

PubMed1992

Effect of parenteral administration of GM1 on cytokines and anti-ganglioside antibody patterns. Preliminary report in normal human individuals.

To assess the effects of monosialoganglioside GM1 on some immunological parameters, 12 healthy men were treated with 100 mg GM1 i.m. daily for 15 days. Before and after treatment, the following were studied: (1) serum levels of antibodies against GM1, asialo-GM1 (aGM1), GM2 and GD1b; (2) serum levels of interleukin (IL)-1 beta, IL-2, soluble IL-2 receptor (sIL-2R), tumor necrosis factor-alpha (TNF-alpha), and interferon-gamma (IFN-gamma); (3) IL-1 beta and TNF-alpha production by peripheral blood monocytes (PBMO). Anti-ganglioside antibody and cytokine serum levels were not affected by exogenous GM1 administration with the exception of a transient increase in anti-GM1 antibody titer observed in one subject. In addition, no inhibition of IL-1 beta and TNF-alpha production by PBMO was observed. These preliminary data do not support a potential immunogenic or immunomodulatory function for in vivo administered GM1.

Adolescent↗

PubMed1991

Induction of antigen-specific CD8+ cytolytic T cells by the exogenous bacterial antigen streptolysin O in rhesus monkeys.

We have characterized the T cell responses induced by streptolysin O (SLO), a sulfhydryl-activated hemolysin secreted by streptococci, by applying long-term in vitro culture and cloning rhesus monkey (Macaca mulatta) T cells. T cell lines specific for SLO were obtained from three rhesus monkeys. These T cell lines required autologous antigen-presenting cells (APC) to proliferate in response to SLO and did not respond to purified protein derivative. Phenotypic analysis showed that the cells from two of three SLO-specific T cell lines were more than 85% CD3+CD4-CD8+ after prolonged in vitro culture. The rh 1842 CD8+ T cell line proliferative response to SLO was inhibited by the addition of anti-major histocompatibility complex (MHC) class I and anti-CD8 but not of anti-MHC class II and anti-CD4 monoclonal antibody (mAb). This cell line was able to lyse P815 target cells in the presence of anti-CD3 mAb and did not show natural killer activity. Moreover, specific lysis of autologous but not allogeneic non-rosetting E- cell targets pulsed with SLO was observed. Such lysis was inhibited by the addition of anti-MHC class I mAb. In the attempt to identify the restriction elements involved in SLO presentation APC from six unrelated rhesus monkeys and three humans were used. A CD4+ rh 1842 T cell clone responded when SLO was presented by one of six, and a CD8+ rh 1842 T cell clone by four of six rhesus monkeys APC. Both CD4+ and CD8+ T cell clones did not respond when SLO was presented by human APC. However, both clones responded when APC from all donors were used in conjunction with anti-CD3 mb. Furthermore, SLO required active processing to be presented to CD4+ and CD8+ T cell clones as glutaraldehyde fixation of APC before but not after antigen pulsing inhibited T cell proliferation. The SLO-specific CD8+ cytolytic T cells described here could play a role in the regulation of the immune response occurring during streptococcal infections and/or could participate in the pathogenesis of poststreptococcal nonsuppurative sequelae.

Animals↗

PubMed1991

In vivo decreased expression of CD25 (p55 chain of IL-2 receptor) on CD3+ T cells correlates with low in vitro responsiveness to Plasmodium falciparum antigen in subjects living in a malaria endemic area.

Significant proliferative responses of peripheral blood mononuclear cells (PBMC) to crude Plasmodium falciparum schizont antigen (M.Ag) or purified recombinant 31.1 Ag (part of gp 195) were observed only in 46 and 39%, respectively, of 50 healthy subjects 5 to 63 years old living in Gabon, a malaria-endemic area. High responses to pokeweed mitogen were observed in all the subjects except one. Interferon-gamma (IFN-gamma) production paralleled the proliferative response, but in some subjects proliferation without a IFN-gamma response was observed. The proportion of subjects responding to M.Ag and 31.1 Ag increased with age. By cytofluorometric analysis performed with PBMC from 27 subjects, a substantial proportion of CD3+ T cells was found to bear the activation marker HLA-DR. However, the CD3+ cells expressed very low levels of CD25 (p55 chain of IL-2 receptor). The expression of CD25 on T cells and their capacity to respond to M.Ag were significantly correlated. In four subjects an increase in the percentage of CD3+ cells bearing the very late activation marker VLA-1 was observed.

Adolescent↗

PubMed1991

Epstein-Barr virus transformation of Saimiri sciureus (squirrel monkey) B cells and generation of a Plasmodium brasilianum-specific monoclonal antibody in P. brasilianum-infected monkeys.

The new-world monkeys Saimiri sciureus (squirrel monkeys) are currently used as a model to test the efficacy of vaccines against human malaria. To improve our knowledge on this model, we tested the susceptibility of S. sciureus B cells to Epstein-Barr virus (EBV) infection. B-lymphoblastoid cell lines were obtained from six of six healthy animals after infection with the B95-8 source of EBV. The frequency distributions of spleen B cells clonally committed to the production of immunoglobulins M and G, as measured by limiting dilution analysis, were from 1 in 179 to 1 in 1,085 and from 1 in 45 to 1 in 60, respectively, in three monkeys naturally infected with Plasmodium brasilianum. In the same three animals, the frequency of spleen B cells committed to the production of P. brasilianum-specific antibody ranged from 1 in 2,211 to 1 in 9,099. One B-lymphoblastoid cell line producing anti-P. brasilianum-specific antibody was cloned twice, and the immunoglobulin G produced was purified. This monoclonal antibody recognized a parasite component of 197 kDa and was specific for Plasmodium malariae and P. brasilianum parasites. These data document that squirrel monkey B cells naturally primed by an infectious agent can be efficiently used to produce monospecific antibodies against the infectious agent.

Animals↗

PubMed1991

Isotypic analysis, antigen specificity, and inhibitory function of maternally transmitted Plasmodium falciparum-specific antibodies in Gabonese newborns.

An analysis of Plasmodium falciparum-specific antibodies was performed in pairs of maternal and cord sera from Gabon, a region endemic for malaria. All paired sera (n = 59) had P. falciparum-specific antibodies. Immunofluorescence assays detected parasite-specific IgG1, IgG2, and IgG3 in 100% of the tested pairs (n = 26) and IgG4 in 42% of them. The titers of specific IgG2 and IgG3 were significantly lower in cord than in maternal sera. All maternal sera had specific IgM. Of the seven P. falciparum-IgM positive cord sera, six were associated with malaria-related histological placental changes (MRHPC). In addition, higher titers of specific IgG1 in maternal and cord sera and of specific IgG3 in cord sera were associated with MRHPC. Similar P. falciparum antigens were recognized by cord and corresponding maternal sera in radioimmunoprecipitation and Western blot assays (n = 40). Sixteen of 20 cord sera and 15 of 20 paired maternal sera significantly inhibited in vitro parasite growth. The extent of inhibition did not correlate with the titer of specific antibodies. These data confirm the very effective placental transfer of anti-malarial antibodies. The presence of IgM in some cord sera raise the question of intrauterine sensitization to malaria antigens.

Animals↗

PubMed1990

Interleukin-2 reverses T cell unresponsiveness to Plasmodium falciparum-antigen in malaria immune subjects.

Peripheral blood mononuclear cells (PBMC) from a large proportion of 34 healthy adult native residents in a malaria endemic area showed null or marginal proliferative response (low-responders) to schizont-enriched Plasmodium falciparum malaria antigen (M.Ag) but good response to pokeweed mitogen. In contrast, substantial proliferative response to M.Ag was observed in 8/8 adult temporary residents with a history of one to three acute malaria episodes. Purified CD4+ T cells preferentially responded to M.Ag, however in low-responders CD4+ T cell proliferation was poor. Moreover, no inhibition of CD4+ T cell proliferation was observed when graded numbers of CD8+ T cells were added in culture. The addition of recombinant interleukin 2 (rIL-2) to M.Ag restored the proliferative response of low-responders' PBMC. This response was M.Ag-specific when CD4+ T cells grown in M.Ag plus rIL-2, but not in rIL-2 alone, were tested in secondary cultures.

Animals↗

PubMed1990

Defective in vitro production of anti-Plasmodium falciparum antibodies in some malaria-immune subjects.

The cell requirements for immunoglobulin (Ig) and Plasmodium falciparum-specific antibody production in the presence of schizont-enriched malaria antigen (M.Ag) were studied in vitro. Cell donors were healthy immune adult Africans and Europeans who had experienced single P. falciparum acute infection. In the presence of M.Ag a dose-dependent increase in polyclonal IgM and IgG levels was observed with T/B cell cultures from 4/4 European and from 4/14 African donors (high-Ig producers). In 10/14 Africans M.Ag failed to induce significant Ig production (low-Ig producers). No differences in Ig levels between high- and low-Ig producers were observed in the presence of pokeweed mitogen (PWM). The addition of CD8+T cells to CD4+T/B cell cultures significantly suppressed the Ig production in PWM- but not in M.Ag-activated cultures. High levels of P. falciparum-specific antibodies were found in M.Ag-activated cultures from high-Ig producer Africans but not in cultures from Europeans or from low-Ig producer Africans. The in vitro production reflected differences in plasma levels of specific antibodies.

Adolescent↗

PubMed1990

T lymphocyte interferon-gamma production induced by Plasmodium falciparum antigen is high in recently infected non-immune and low in immune subjects.

Interferon (IFN) alpha and gamma were measured by radio-immunoassays in supernatants from cultures of peripheral blood mononuclear cells (PBMC) or purified T cell subsets incubated with either Plasmodium falciparum schizont-enriched malaria antigen (mAg), uninfected red blood cells (RBC) or pokeweed mitogen (PWM). Cell donors were 24 clinically immune, healthy African adult native residents of a P. falciparum-endemic region, Haut-Ogooué, Gabon, and seven non-immune, European temporary residents with a history of a single to a few malaria infections during the previous 1 to 9 months. When PBMC were cultured in medium alone or with RBC antigen no or low titres of IFN-gamma were detected. PBMC proliferation and IFN-gamma production observed in the presence of mAg were dose dependent and significantly correlated. When cultured with mAg, PBMC from non-immune Europeans produced significantly higher levels of IFN-gamma than did PBMC from clinically immune Africans. No such difference was found when PBMC were cultured with PWM. The mAg-induced IFN-gamma production was due mainly to CD4+ T cells and was not enhanced by CD8+ T cell depletion. No IFN-alpha was detected in culture supernatants. Thus, P. falciparum antigens are able to induce in vitro production of IFN-gamma by CD4+ T cells; however, in this sample, individuals considered to be clinically resistant to malaria were low producers of IFN-gamma.

Animals↗

PubMed1988

Natural antibodies against three distinct and defined antigens of Plasmodium falciparum in residents of a mesoendemic area in Gabon.

The magnitude of the antibody response to three distinct and defined antigens of Plasmodium falciparum was assessed in 144 inhabitants of the Kassa district (Haut Ogooué Province, Gabon), a region where malaria is mesoendemic. Antibodies against a polypeptide consisting of 40 (Asn-Ala-Asn-Pro) repeats of P. falciparum circumsporozoite protein [(NANP)40] were detected by ELISA. Antibodies against the fusion peptide 31.1, which consists of the N-terminal portion of the 190-200 kDa glycoprotein, were also detected by ELISA. Antibodies against ring-infected erythrocyte surface antigens (RESA), mainly the P. falciparum 155 kDa antigen (Pf 155), were detected by IFA on glutaraldehyde-fixed P. falciparum infected red blood cells (IRBC). In addition, a standard IFA employing air-dried P. falciparum IRBC was used to detect antibodies against intraerythrocytic asexual forms. Parasitemia and spleen enlargement were also recorded. The frequency of sera positive for specific antibodies increased with age for all the antigens tested. Plateau antibody levels were reached at different ages for the different antigens. Individual antibody responses varied in titer to the different antigens. Subjects with parasite-negative thick smears showed higher titers of anti-31.1 as well as an increased frequency of anti-RESA antibodies compared to subjects having positive smears. No differences in the titer and in the prevalence of anti-(NANP)40 antibodies were found between these groups. The results suggest that the antibody response against asexual blood stage antigens, especially anti-RESA and anti-31.1, may play a role in controlling parasitemia.

Adolescent↗

PubMed1988

Immunogenicity of a non-repetitive sequence of Plasmodium falciparum circumsporozoite protein in man and mice.

In the present work, the hypothesis that individuals naturally exposed to Plasmodium falciparum malaria infection in endemic areas produce antibodies directed against non-repetitive epitopes of the circumsporozoite protein was investigated. Using a synthetic peptide reproducing the non-repetitive group-conserved region I sequence, we have shown that specific anti-region I antibodies are detectable in sera from endemic countries. Of these sera, 87% also had antibodies against the immunodominant repetitive epitope (Asn-Ala-Asn-Pro, NANP) of P. falciparum. In order to study the immunogenicity of this non-repetitive epitope, a synthetic peptide consisting of both region I and three (NANP) repeats [RI-(NANP)3] was used to immunize inbred strains of mice. H-2b mice produced antibodies against both the repetitive and the non-repetitive epitope. These antibodies were specific for each epitope, recognized P. falciparum sporozoites in immunofluorescence, and inhibited sporozoite penetration into human liver cells in vitro. Non-H-2b mice were completely unresponsive. Lymph node cells from H-2b mice immunized with RI-(NANP)3 peptide proliferated in the presence of RI-(NANP)3 and of (NANP)4 peptide, but never in the presence of RI peptide alone. These findings demonstrate that in the configuration used (i) the non-repetitive epitope region I does not carry T-helper epitopes; (ii) the (NANP) repetitive epitope may act as a carrier for the immune response to region I in mice; and (iii) therefore, immune response to region I in man probably depends on the recognition of T-cell epitopes similar to those involved in the anti-NANP response: i.e. such a T epitope may be NANP itself in responding individuals or another, not yet recognized, sporozoite T-cell epitope.

Amino Acid Sequence↗

PubMed1987

Malaria specific human T cell clones: crossreactivity with various plasmodia species.

Peripheral blood mononuclear cells (PBMC) from donors with or without previous exposure to malaria in vivo were cultivated for 4 to 7 days in the presence of different malaria antigen (M.Ag) preparations: Plasmodium falciparum (P.f.Ag), P. berghei (P.b.Ag) and P. gallinaceum (P.g.Ag). All preparations induced a proliferative response in PBMC from donors with or without previous exposure to malaria. PBMC from both groups of donors were then primed with each of the three M.Ag and cloned in presence of autologous irradiated PBMC and M.Ag. All 152 clones recovered had the T4+ phenotype and required autologous antigen presenting cells (APC) in addition to M.Ag for proliferation. Species specific and crossreactive T cell clones (T cell clones proliferating in the presence of the three M.Ag preparations) were recovered following priming with each of the three M.Ag. Species specific and crossreactive T cell clones were recovered in similar percentages (approximately 50%) using PBMC from donors with or without previous exposure to malaria. These data are discussed in the context of crossreactivity at the T cell level among various plasmodia species and in relation to epitope recognition of malaria native, synthetic and fusion polypeptides.

Adult↗

PubMed1986

Antigen-specific and MHC-restricted Plasmodium falciparum-induced human T lymphocyte clones.

We established and analyzed human T lymphocyte clones induced by crude Plasmodium falciparum antigens of schizont-enriched asexual blood stages. Peripheral blood mononuclear cells (PBMC) were stimulated for 6 days with antigen, and the T cell blasts were separated and were transferred to limiting dilution cultures with antigen, irradiated PBMC, and recombinant interleukin 2. The following observations were made. Malaria antigen (M.Ag) induced similar proportions of T blasts in PBMC from infected individuals and noninfected controls, and the M.Ag-dependent clone frequencies (1/79 to 1/216) obtained with the blasts were similar. The majority of established clones derived from infected and noninfected subjects specifically recognized M.Ag and would not proliferate in response to red blood cells or autologous PBMC alone. They also required HLA class II determinant-compatible antigen-presenting (E-) cells. With three clones from one malaria patient, DR 1 or DR 5 specificities correlated with antigen presentation. Although T4+ and T8+ blasts were induced by M.Ag in PBMC, only T4 (Leu-3+) clones were obtained in our culture system. These clones secreted IL 2 in response to M.Ag. 4) Differential patterns of reactivity to native M.Ag, heat-stable antigens, and heat-precipitated antigens were exhibited by T cell clones, and the tested clones did not recognize Plasmodium berghei antigen. In conclusion, it is important with regard to previous observations on apparently nonspecific, mitogen-like effects of M.Ag in bulk T cell cultures that our results demonstrate specific recognition of P. falciparum by human T cells. The T cell clones obtained will be an important tool in the quest for a better understanding of the mechanisms involved in resistance to malaria infection.

Adult↗

PubMed1986

Immunization with synthetic peptides of a Plasmodium falciparum surface antigen induces antimerozoite antibodies.

Polypeptides expressed on the surface of merozoites, the invasive stage of the asexual blood cycle, are good candidates for the development of malaria vaccines. Five synthetic peptides with predetermined specificity deduced from a genomic DNA clone coding for the NH2-terminal portion of the main merozoite surface polypeptide of Plasmodium falciparum were evaluated for their capability to raise antibodies that react with the P. falciparum merozoites. Antibodies induced by two of the peptides (3 and 5) reacted with the membrane surfaces of seven of seven isolates of P. falciparum from different geographic areas. Antibodies against peptide 4, which contains a repeated amino acid sequence (Gly-Gly-Ser and Val-Ala-Ser), reacted with six of seven isolates. Structural analysis of the deduced polypeptides suggests that peptide 3 is exposed at the surface of merozoites. When it was used to immunize monkeys, three of the four animals were partially protected from a challenge infection that induced a fulminant infection in control animals.

Amino Acid Sequence↗

PubMed1985

Immunization with a Plasmodium falciparum merozoite surface antigen induces a partial immunity in monkeys.

Saimiri monkeys immunized with a Plasmodium falciparum merozoite polypeptide of 41 kD mol wt are resistant to a blood challenge infection that induces a fulminant infection in control monkeys. The sera of the immunized monkeys reacted, as shown by the indirect immunofluorescence technique, with the apical part of the merozoites from five isolates or clones of P. falciparum. Whether the immunogen was dissolved in nonionic detergent (NP-40) or in sodium dodecyl sulfate (SDS) had a marked influence on the level of protection in immunized monkeys. Thus, monkeys immunized with the antigen solubilized in a nonionic detergent developed much lower parasitemia than monkeys immunized with denatured antigen (antigen eluted from SDS polyacrylamide gel electrophoresis).

Animals↗