Papers by Ises Abrahamsohn
<p>(A) C57BL/6 mice were treated with JES6-1 mAb on days 0, 2 and 4 p.i. with 10<sup>... more <p>(A) C57BL/6 mice were treated with JES6-1 mAb on days 0, 2 and 4 p.i. with 10<sup>6</sup> PRBC. On day 7 p.i., splenic CD4<sup>+</sup> T cells were analyzed for CD122, CD25, CD69 and CD44 expression and cell size (FSC). Data show gated CD4<sup>+</sup> T cells expressing high levels of activation markers and large size (n = 3–4). (B) Non-stimulated (basal) and anti-CD3 mAb stimulated IFN-γ and IL-17 production was evaluated in CD4<sup>+</sup> T cells from the same groups of mice. (C) Numbers of CD4<sup>+</sup> T cells per spleen were determined in the same groups of mice. (D) On day 4 p.i., PRBC-stimulated CD4<sup>+</sup> T cell proliferation was analyzed <i>in vitro</i> in the presence or absence of JES6-1 mAb. Histograms show CFSE fluorescence in gated CD4<sup>+</sup> T cells. The means ± SD (n = 3–4) of the percentages of replicating (CFSE<sup>LO</sup>) cells are shown. In A–D, significant differences compared experimental conditions *p<0.05 with cells from non-infected (NI) mice; **p<0.05 with cells from non-treated (NT) mice; and #p<0.05 with non-stimulated cells. Data are representative of three separate experiments.</p
<p>(A) IL-2 secretion was analyzed in gated CD4<sup>+</sup> T cells obtained fr... more <p>(A) IL-2 secretion was analyzed in gated CD4<sup>+</sup> T cells obtained from C57BL/6 mice on days 3, 5, 7 and 15 p.i. with 10<sup>6</sup> PRBC. Numbers inside dot plots refer to means ± SD (n = 3–4) of cell percentages in the upper right gate. (B) Cell size (FSC) and expression of CD25 and CD122 were evaluated in gated CD4<sup>+</sup>IL-2<sup>−</sup> and CD4<sup>+</sup>IL-2<sup>+</sup> cells of the same groups of mice. (C) On day 7 p.i., CD122, mTGF-β, CD45RB, CTLA-4 and GITR expression was analyzed in gated CD4<sup>+</sup>CD25<sup>+</sup> cells, subdivided into small and large cells. Numbers inside dot plots refer to means ± SD (n = 3–4) of cell percentages in each gate. The mean fluorescence intensity (MFI) of CD4<sup>+</sup>CD25<sup>−</sup> cells (controls) stained with mAb to mTGF-ß and GITR was comparable to respective isotopic controls (data not shown). In A–C, there was a significant difference (*p<0.05) between experimental conditions and non-stimulated (NS) cells from non-infected mice. Cells from non-infected mice stimulated with anti-CD3 mAb were used as positive controls. Dot plots and histograms show a representative mouse of each group. Data are representative of three separate experiments.</p
<p>(A) C57BL/6 mice were treated with JES6-1 mAb on days 0, 2 and 4 p.i. with 10<sup>... more <p>(A) C57BL/6 mice were treated with JES6-1 mAb on days 0, 2 and 4 p.i. with 10<sup>6</sup> PRBC. On day 30 p.i., TNF-α and IFN-γ production was evaluated in spleen cell supernatants (mean ± SD, n = 4). (B) Serum titers of parasite-specific IgG2a were determined in the same groups of mice. (C) Parasitemia curves were evaluated in C57BL/6 mice injected with spleen cells from JES6-1-treated mice and non-treated (NT) mice on day 30 p.i. and challenged with 10<sup>8</sup> PRBC (mean ± SD, n = 4). In A–B, significant differences compared experimental conditions *p<0.05 with non-infected (NI) mice; and **p<0.05 with non-treated (NT) mice. In C, significant differences compared to experimental conditions *p<0.05 with mice transferred with cells from non-treated (NT) mice. Data are representative of two separate experiments.</p
<p>(A) Parasitemia curves and CD4<sup>+</sup> T cell numbers per spleen were ev... more <p>(A) Parasitemia curves and CD4<sup>+</sup> T cell numbers per spleen were evaluated in C57BL/6 mice infected with 10<sup>6</sup> PRBC (mean ± SD, n = 4). (B) Basal (non-stimulated) proliferation and IFN-γ production in infected mice. Percentages of replicating (CSFE<sup>LO</sup>) CD4<sup>+</sup> T cells and CD4<sup>+</sup>IFN-γ<sup>+</sup> cells are shown (mean ± SD, n = 4). (C) On days 4, 7 and 30 p.i., CD25 and CD122 expression was analyzed in gated CD4<sup>+</sup> T cells. Numbers inside dot plots refer to means ± SD (n = 3–4) of cell percentages in each gate. (D) On day 7 p.i., CD25<sup>−</sup>CD122<sup>+</sup>, CD25<sup>+</sup>CD122<sup>+</sup>, CD25<sup>−</sup>CD122<sup>−</sup> and CD25<sup>+</sup>CD122<sup>−</sup> cells in gated CD4<sup>+</sup> T cells of the same groups of mice were analyzed according to cell size (FSC). Numbers inside histograms refer to means ± SD (n = 3–4) of large cell percentages. In A–D, *p<0.05, compared to non-infected mice (day 0). Dot plots and histograms show a representative mouse of each group. Data are representative of three separate experiments.</p
Parasitology, Dec 1, 1977
SummaryThis paper describesin vitroantibody dependent cytotoxicity againstTrypanosoma cruziepimas... more SummaryThis paper describesin vitroantibody dependent cytotoxicity againstTrypanosoma cruziepimastigotes by normal mouse splenic lymphocytes. Cytotoxicity was expressed as the percentage reduction in the number of motile parasites upon incubation with lymphocytes at 37 °C in a denned medium. Failure of the non-motile parasites to regain motility and their ensuring degeneration at 28 °C in liver infusion tryptose (LIT) medium confirmed loss of motility as a criterion of cytotoxicity. Incubation ofT.cruziat 37 °C for 18 h in a defined mediumper sedid not interfere with motility but was followed by a lag phase of the growth curve in LIT medium at 28 °C. The lag phase was prolonged forT. cruziwhich had previously been incubated at 37 °C in the absence of cells.
Parasitology Research, 1997
The induction of protective immunity to Leishmania amazonensis was investigated by injection of p... more The induction of protective immunity to Leishmania amazonensis was investigated by injection of parasite clones of low and medium virulence into susceptible mice. To this end, L. amazonensis were cloned by limiting dilution and the clones' virulence was evaluated by the course of infection in susceptible mice. Clones originally derived from the spleen showed virulence variations in comparison with that of the parental population (PP) of parasites. Two low-virulence clones (SP 5 and SP 20) and one medium-virulence clone (SP 11), representative of the spectrum of derived clones, were compared with virulent parasites and with an avirulent strain (Josefa) as to their ability to induce T-cell immune responses and to protect BALB/c mice from infection with the virulent L. amazonensis PP. Clone SP 20 and clone SP 11 induced partial protection when injected by the intravenous and intradermal route, respectively. The avirulent Josefa strain induced neither T-cell responses nor protection. Low-virulence L. amazonensis clones can therefore be additional tools in vaccine investigation.
Parasitology, 1980
SummaryLLC-MK2 cell monolayers infected with Trypanosoma cruzi were shown by immunofluorescence t... more SummaryLLC-MK2 cell monolayers infected with Trypanosoma cruzi were shown by immunofluorescence to present parasite antigens on the surface of both parasitized and non-parasitized cells after completion of the first intracellular cycle and rupture of infected cells. The cell-culture supernatant fluid at this stage, as well as the supernatant fluid of parasites left overnight in culture medium were concentrated and contained antigen capable of binding to uninfected cell monolayers. The origin of this antigen, as well as its eventual role in the pathogenesis of Chagas' disease, are discussed.
Memórias do Instituto Oswaldo Cruz, 1987
The Journal of Parasitology, 1983
Journal of Leukocyte Biology, 2003
Production of IL-12 is an important indicator of the macrophage's ability to regulate immune resp... more Production of IL-12 is an important indicator of the macrophage's ability to regulate immune responses. In this study, we investigated the IL-12 production by macrophages in different developmental stages. To this end, macrophages were generated in vitro from precursors stimulated with M-CSF, GM-CSF or IL-3. Density separation yielded populations enriched in different maturation stages. Invariably, only cells banding at the 40؊50% Percoll interface produced large amounts of IL-12p40 when stimulated with LPS, whereas only low levels of IL-12p70 were produced. These cells represented immature macrophages, as indicated by the absence of precursor markers CD31/ER-MP12, Ly-6C/ER-MP20 and ER-MP58, and by the low level of expression of mature-cell markers like ER-HR3, scavenger receptor and CD11b/Mac-1. Upon further maturation, the macrophages' ability to produce IL-12p40 decreased, coinciding with increased nitric oxide production upon LPS stimulation. These results show that immature macrophages produce high levels of IL-12p40 and thus may either contribute to IL-12p70 production or regulate it.
Journal of Immunological Methods, 1987
A specific and sensitive enzyme-linked immunoassay is applied for enumeration of cells secreting ... more A specific and sensitive enzyme-linked immunoassay is applied for enumeration of cells secreting specific antibodies to Trypanosoma cruzi antigens. Spleen cells from immunized mice are incubated in antigen-coated plastic tissue culture plates. Individual antibody-producing cells secrete antibody which binds to the antigen at close vicinity of the cells. The areas of bound antibodies are demonstrated by an enzyme-linked antibody assay as dark round spots, which can be easily enumerated. This assay allows the enumeration of specific antibody-secreting cells to parasite antigens, overcoming the failures to develop conventional plaque-forming cells assays to complex antigens.
Immunology Letters, 1998
The massive infiltration by polymorphonuclear leukocytes (PMN) soon after skin infection with Lei... more The massive infiltration by polymorphonuclear leukocytes (PMN) soon after skin infection with Leishmania major suggests that PMN could participate in reducing parasite load and controlling the spreading of leishmanial infection. Yet, direct evidence for the participation of PMN in host defense against L. major was lacking. We investigated L. major infection in susceptible and resistant mice treated with the monoclonal (mAb) antibody RB6-8C5 that depletes the population of mature neutrophils and eosinophils. Both BALB/c and C57BL/6 mice depleted of PMN show accelerated parasite spreading and more severe footpad swelling than similarly infected untreated mice. In addition, significant higher parasite numbers were found in the lesion draining lymph nodes from PMN-depleted C57BL/6 mice. Histopathological analysis of the paw confirmed neutrophils containing ingested parasites as the dominant cell type in the infiltrate of the first days after infection and the nearly absolute neutrophil depletion in mAb-treated mice. Our data show the importance of PMN in early control of parasite load and parasitism spreading in cutaneous leishmaniasis.
Immunology Letters, 1998
T. cruzi-infected macrophages are potential candidates for the presentation of parasite antigens ... more T. cruzi-infected macrophages are potential candidates for the presentation of parasite antigens to T. cruzi-specific T lymphocytes. To assess this question, we examine the ability of peritoneal exudate macrophages to process exogenous live or dead parasites and to activate defined populations of T. cruzi-specific immune T-cells. Macrophages infected with live amastigotes activated both lymph node CD4+ and spleen CD8 + T-primed cells that proliferated and secreted cytokines. Lymph node CD4+ T-cells produced IFN-gamma and IL-10 while CD8 + T-cells produced IFN-gamma. In contrast, macrophages pulsed with dead parasites activated only lymph node CD4+ T-cells, which proliferated and secreted IFN-gamma. Interestingly, the immunization with heat-killed parasites primed mice for CD8+ T-cells which were expanded in vitro by recognition of infected macrophages. Taken together, these results demonstrated that amastigote infected macrophages present parasite peptides associated with MHC I and II molecules, activating both CD4 + and CD8+ T-cells. Furthermore, the development of T. cruzi-specific CD8+ T-cells in vivo using the immunization protocol with non-living parasites as described in this report could be explored for further studies on the role of CTL in the outcome of infection.
Immunology Letters, 1997
Chagas&#39; disease is caused by infection with Trypanosoma cruzi. Patients in the chronic ph... more Chagas&#39; disease is caused by infection with Trypanosoma cruzi. Patients in the chronic phase of infection were grouped as belonging to the asymptomatic (or indeterminate), cardiac and cardiac plus digestive forms. Previous studies have described abnormal immune responsiveness by peripheral blood mononuclear cells (PBMC) from chronic chagasic patients. We report significant parasite antigen (T-Ag)-stimulated PBMC proliferative responses to be present in all three groups of patients. Treatment of T-Ag-stimulated cultures with rIL-12 significantly amplifies proliferative responses in all patients&#39; groups, with similar rates of increment. IL-12 enhances T-Ag-specific lymphoproliferation without increasing proliferation of unstimulated PBMC from normal individuals or from patients. Comparatively, treatment with rIL-2 enhances both T-Ag-specific and unstimulated proliferation by PBMC from patients and normals. Thus, IL-12 acts on pre-activated cells while IL-2 also stimulates resting cells. No synergism was obtained by the combined use of IL-12 and IL-2. Therefore IL-12 can act as a more selective amplifier of T. cruzi reactive cells than IL-2. IL-12, by enhancing parasite-antigen specific immunity, could be of potential therapeutic use to control reactivated T. cruzi infections concomitant to AIDS or other situations of immunosuppression.
Immunology & Cell Biology, 2003
The pure delayed-type hypersensitivity reaction obtained in 4-day ovalbumin-sensitized mice after... more The pure delayed-type hypersensitivity reaction obtained in 4-day ovalbumin-sensitized mice after antigen challenge in the footpad was abrogated by transfer of in vitro expanded, antigen-specific lymphoblasts derived from ovalbumin-hyperimmunized donors (high antibody producers), 12 h before immunization. This effect was specific inasmuch as Trypanosoma cruzi-specific blasts derived from Tc-Ag-hyperimmunized mice did not inhibit delayed-type hypersensitivity in ovalbumin-immunized recipients. The ovalbumin-specific blasts displayed a Th2 cytokine profile, secreting IL-4 and IL-10 upon restimulation in vitro with ovalbumin, but not IFN-γ or IL-2. In addition, recipients of such cells produced much more IgG1 and IgE antibodies. When the frequency of T-cell blasts was enriched among these cells, transfer of four million cells was enough to prevent the induction of delayed-type hypersensitivity. Neutralization of IL-4 alone just before cell transfer not only restored the delayed-type hypersensitivity reaction, but also maintained it in a plateau for at least 72 h after challenge. Recipients treated in this way also showed a shift back towards a Th1 phenotype, indicated by the increase in IL-2, IFN-γ and IL-12 synthesis. No synergistic action was observed when IL-4 and IL-10 were concomitantly neutralized. These results indicate that activation of Ag-specific Th2 cells early in the course of the immune response to a protein antigen provides an immunological environment rich in IL-4, thus leading to the inhibition of cell-mediated immunity.
Immunology, 2001
Delayed-type hypersensitivity reactions elicited in the footpad of ovalbumin-sensitized mice afte... more Delayed-type hypersensitivity reactions elicited in the footpad of ovalbumin-sensitized mice after challenge with aggregated ovalbumin on day 4 or 8 of immunization are distinct. The former was characterized by a dense mononuclear in®ltrate and, macroscopically, the reaction peaked at 48 hr after antigen challenge; the latter was preceded by immediate-type reactions, reached the maximum at 24 hr and faded drastically later. Histologically, oedema and a mixed granulocytic±lymphocytic in®ltrate was found at this time-point. Immunoglobulin G1 (IgG1), IgG2a and IgE antibodies were detected only in plasma obtained after 8 days of immunization. Regarding the cytokines produced by draining lymph node cells after in vitro restimulation, interleukin-4 (IL-4) and IL-10 were predominant after 4 days and interferon-c and IL-2 after 8 days of immunization. These two types of delayed-type hypersensitivity (DTH) were used to study the in¯uence of antibody-mediated responses on the inductive and effector phases of cell-mediated immunity. The effector phase of DTH was not affected by immediate-type reactions, as abrogation of these reactions by mediators' antagonists on day 8 or induction of passive reactions by transfer of immune serum on day 4 did not change the extent or kinetics of either type of DTH. Only transfer, before immunization, of whole or T-cell-enriched spleen cells, but not sera, from hyperimmunized donors (high antibody producers) abolished the induction of pure DTH in 4-day immunized recipient mice and changed their cytokine pro®le to a T helper 2 type. These results indicate that in a non-polarized immune response to a protein antigen there is initially a bias towards cell-mediated immunity, which is gradually dampened by the development of antibody-mediated immunity.
PloS one, 2012
Plasmodium chabaudi infection induces a rapid and intense splenic CD4(+) T cell response that con... more Plasmodium chabaudi infection induces a rapid and intense splenic CD4(+) T cell response that contributes to both disease pathogenesis and the control of acute parasitemia. The subsequent development of clinical immunity to disease occurs concomitantly with the persistence of low levels of chronic parasitemia. The suppressive activity of regulatory T (T(reg)) cells has been implicated in both development of clinical immunity and parasite persistence. To evaluate whether IL-2 is required to induce and to sustain the suppressive activity of T(reg) cells in malaria, we examined in detail the effects of anti-IL-2 treatment with JES6-1 monoclonal antibody (mAb) on the splenic CD4(+) T cell response during acute and chronic P. chabaudi AS infection in C57BL/6 mice. JES6-1 treatment on days 0, 2 and 4 of infection partially inhibits the expansion of the CD4(+)CD25(+)Foxp3(+) cell population during acute malaria. Despite the concomitant secretion of IL-2 and expression of high affinity IL-2...
Experimental Parasitology, 1990
Mice infected with 5 x 10(3) forms of Trypanosoma cruzi showed a transient, but severe impairment... more Mice infected with 5 x 10(3) forms of Trypanosoma cruzi showed a transient, but severe impairment of in vitro spleen cell responses to parasite antigens and to Concanavalin A (Con A). In contrast, inguinal and periaortic lymph node (LN) cells displayed high parasite-specific proliferative responses and only a partial reduction of the Con A-induced proliferation during the acute and chronic phases of infection. Lymphocytes that underwent blastic transformation in T. cruzi-stimulated cell cultures were of the L3T4+ phenotype. Suppression of spleen cell responses occurred in the acute phase whether mice were infected with high (3 x 10(5] or low (5 x 10(3] doses of T. cruzi by intraperitoneal or subcutaneous route. Suppression of the T. cruzi-specific proliferative response of LN cells was only observed in mice infected with high subcutaneous inocula. This suppression, however, was restricted to the LNs draining the site of inoculation without affecting distant LNs. Supernatants from parasite-stimulated proliferating LN cells displayed low or undetectable T cell growth factor (TCGF) activity, in contrast with the high TCGF levels found in supernatants of the same cells stimulated with Con A. Low levels of TCGF were also detected in cultures of LN cells from mice immunized with T. cruzi extracts. Neither the T. cruzi antigen used for in vitro stimulation nor the LN cell supernatants from infected mice inhibited TCGF activity. These findings indicate that (1) parasite-specific responses are present in the LN compartment throughout the acute phase of T. cruzi infection in mice and (2) the proliferative response of L3T4+ LN cells from infected mice to T. cruzi antigens is not associated with a high TCGF secretory response.
Cellular Immunology, 1996
of parasite-specific host cells toward a Th2 phenotype. ᭧ 1996 Academic Press, Inc. Control of ma... more of parasite-specific host cells toward a Th2 phenotype. ᭧ 1996 Academic Press, Inc. Control of macrophage parasiticidal function by treatment with recombinant cytokines or their neutralizing antibodies modifies the severity of experi-INTRODUCTION mental Trypanosoma cruzi infections. However, so far, no direct in vivo evidence has demonstrated Trypanosoma cruzi is a dygenetic protozoan which changes in disease outcome after altering the initial infects several kinds of mammals and is the etiologic ratios of parasite-specific IFN-g and IL-10/IL-4-seagent of Chagas' disease in humans. Multiple genes cretor cells in secondary lymphoid organs. To this outside the H-2 locus determine the outcome of infecend, a population of predominantly CD4 / parasitetion in the mouse and yet a spectrum of resistance Ag-reactive, IL-4-and IL-10-secreting T lymphocytes patterns is found among inbred strains (1). C3H and derived from T. cruzi-immunized mice was adop-A mice generally rank as the most susceptible, whereas tively transferred to naive recipients. Compared C57BL/6 and SJL mice are more resistant, although with cell responses from normal mice, spleen cells of uninfected recipients proliferated significantly to T. such distinctions may eventually vary depending on cruzi Ag and produced much greater amounts of IL-the strain of T. cruzi studied (2). Efficient control of 4 and IL-10; lower IFN-g levels and increased IL-4/ parasite load and host survival rely on T-cell-mediated IL-10 levels were induced by Con A stimulation. Reimmunity via T-helper-cell-dependent protective Ab recipient mice challenged with T. cruzi presented oversponses and macrophage activation for intracellular whelming tissue and blood parasitemia and early killing of the protozoan. In addition, class I-dependent death, contrasting with typically resistant controls. effector mechanisms have been recently shown to play Uninfected recipients did not exhibit tissue damage an important role in host defense against T. cruzi (3, 4). following cell transfer. No disease exacerbation oc-Nevertheless, the mounting of an immune response curred in recipients of OVA-reactive CD4 / , IL-4/ILdoes not ensure total elimination of the parasites, 10-secreting T lymphocytes stimulated with OVA at which persist in low numbers in the vertebrate host the start of infection. On Day 6 postinfection, not throughout life. only spleen cells but also LN cells from infected re-Available data have demonstrated that several maccipients showed decreased production of IFN-g and rophage-activating or-deactivating cytokines deteraugmented secretion of IL-4/IL-10 compared to cells mine the fate of intracellular T. cruzi amastigotes in from untransferred infected mice. The results indivitro. The addition of IFN-g (5-8), GM-CSF (9), IL-4 cate that an imbalance of Th cell populations leading (10), or TNF-a (8, 11, 12) to cultures of T. cruzi-infected to the predominance of secreted IL-4 and IL-10 at the macrophages results in more efficient killing of amastistart of infection and the concomitant down-regulagotes by the phagocytes, whereas the addition of TGFtion of IFN-g secretion reversed the host's resistance b or IL-10 inhibits the trypanocidal action of INF-gto T. cruzi. Moreover, transfer of anti-T. cruzi Th2activated macrophages (13-15). type cells most likely favored the in vivo expansion Most importantly, the in vivo administration of IFNg (16) early during infection effectively reduces blood parasitism and mortality in mice, whereas in vivo
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Papers by Ises Abrahamsohn