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H M Serra

Publications and source records attributed to H M Serra.

At least 19 recordsLinked to original sources
PubMed2003

Expression of CS-1 fibronectin precedes monocyte chemoattractant protein-1 production during elicitation of allergic contact dermatitis.

BACKGROUND: Leucocyte migration within inflammatory skin compartments in allergic contact dermatitis (ACD) is the result of a sophisticated multi-step event where multiple molecules are involved. OBJECTIVE: Since non-antigen-specific mechanisms have been described as an early participant in elicitation of ACD, we investigated the kinetics of the expression of monocyte chemoattractant protein-1 (MCP-1/CCL2) and the type of infiltrating cells. We compared the time course production of MCP-1/CCL2 with connecting segment-1 (CS-1) fibronectin and thymus and activation-regulated chemokine (TARC/ CCL17) expression. METHODS: Biopsies from 10 individuals challenged in their back with the antigen responsible for their contact dermatitis and an irrelevant antigen were taken at different times and histology, immunohistochemistry for CS-1 fibronectin, TARC/CCL17, CD3, CD68, CXCR3, CCR4 and in situ hybridization for MCP-1/CCL2 were performed. RESULTS: At positive antigen stimulated sites expression of MCP-1/CCL2 by basal keratinocytes and isolated cells in dermis started at 10 h. CS-1 fibronectin and TARC/CCL17 expression by blood endothelial cells was found at 2 and 10 h, respectively. This was followed by dermal accumulation of mononuclear cells with a significant increase of CD3+ and CD68+cells. At 48 h, approximately 58% of infiltrating cells were CXCR3+, and 35% CCR4+. CONCLUSIONS: We showed evidence of the fact that CS-1 fibronectin expression precedes the production of MCP-1/CCL2 and TARC/CCL17 in the skin of patients with ACD, suggesting that these molecules participate in the early complex process of migrating mononuclear cells during elicitation of ACD.

Adult↗
PubMed1996

Involvement of accessory cells in the Trypanosoma cruzi-induced inhibition of the polyclonal response of T lymphocytes.

Infection with Trypanosoma cruzi is characterized by hyporesponsiveness of the immune system during the acute phase of infection. To better understand the immunological mechanisms affected by T. cruzi, we studied if a reduced T cell proliferative response could originate from an inability of T cells to proliferate or a functional deficiency at the level of accessory cells (AC). The inhibitory effect exerted by T. cruzi was during the induction phase of the lymphoproliferative response, suggesting the participation of AC in the hyporesponse. Then we further investigated the potential of the parasite to interfere with accessory cell-dependent and -independent pathways of human T cell proliferation. Peripheral blood mononuclear cells and peripheral blood lymphocytes from healthy individuals, enriched for T cells, were analysed with regard to their proliferative capacity using: phytohaemagglutinin, immobilized anti-CD3 monoclonal antibody (MoAb) and MoAb to the CD28 antigen, anti-CD3 MoAb and recombinant IL-2 and anti-CD3 MoAb plus phorbol myristate acetate in the presence of parasites. Significant suppression of the proliferative response was caused by the parasite only when AC were present. The parasite markedly reduced the surface expression of HLA-DR and CD11b antigens, key molecules in PHA-induced proliferation. Addition of indomethacin to the culture failed to reverse the inhibitory effect of the parasites, suggesting that prostaglandin E2 was not involved. These data suggest that AC in contact with T. cruzi become incompetent as antigen presenting cell because they are unable to induce a normal proliferative response in T lymphocytes.

Animals↗
PubMed1995

In vitro induction of primary, antigen-specific CTL from human peripheral blood mononuclear cells stimulated with synthetic peptides.

A protocol for in vitro induction of primary, antigen-specific CTL from human peripheral blood mononuclear cells (PBMCs) was developed. Antigen presenting cells (APCs) consisted of Staphylococcus aureus Cowan-I (SAC-I) activated PBMCs treated with a citrate-phosphate buffer at pH 3 to release endogenous peptides bound to surface MHC. This treatment resulted in transient expression of empty class I molecules which could be subsequently stabilized with peptide and beta 2-microglobulin (beta 2m). SAC-I activated PBMCs from HLA-A2.1 normal donors loaded with HBV core 18-27 peptide following acid treatment were used to stimulate PBMCs depleted of CD4+ T cells, in the presence of recombinant interleukin-7 (rIL-7). After 12 days, cells were restimulated with autologous, peptide-pulsed, adherent cells and tested for CTL activity 7 days later. In 23 independent experiments from 13 different HLA-A2.1 donors, this protocol resulted in induction of primary CTL more than 90% of the time. As indicated by both the frequency and magnitude of the response against peptide-sensitized target cells, SAC-I activated PBMCs treated with acid were the most efficient stimulator APC. Thirteen per cent of the cultures generated were capable of lysing target cells transfected with the HBV core antigen and, in general, these CTL cultures exhibited high avidity for the HBV core peptide. This protocol is generally applicable to different antigens and class I alleles, and thus, may be utilized to screen large numbers of peptides to identify human CTL epitopes.

Antigen-Presenting Cells↗
PubMed1994

Induction of anti-tumor cytotoxic T lymphocytes in normal humans using primary cultures and synthetic peptide epitopes.

Cytotoxic T lymphocytes (CTLs) recognize peptide antigens associated with cell surface major histocompatibility complex (MHC) molecules. The identification of tumor cell-derived peptides capable of eliciting anti-tumor CTL responses would enable the design of antigen-specific immunotherapies. Our strategy to identify such potentially therapeutic peptides relies on selecting high-affinity MHC binders from known tumor-associated antigens. These peptides are subsequently tested for their ability to induce CTLs capable of killing tumor cells. With this strategy, we have identified a nine-residue epitope, derived from the product of the tumor-associated gene MAGE-3, which has the capacity to induce in vitro CTLs that kill melanoma and other tumor cell lines. These results show the primary in vitro induction of tumor-specific human CTLs and illustrate the feasibility of ex vivo antigen-specific approaches to the immunological therapy of cancer.

Amino Acid Sequence↗
PubMed1994

Antibody isotypes profiles against Trypanosoma cruzi acidic antigens in two Amerindian populations from a Chagas' disease endemic area.

The isotype distribution of the antibody response against one Trypanosoma cruzi antigenic fraction, FIV, and the putative association to heart disease were analyzed in patients of two apparently genetically distinct Amerindian populations, Mataco (M) and Toba (T), infected with this parasite. The isotypes profiles were analyzed by ELISA, and the antigen specificity of IgG immune response was determined by the immunoblot method. The percentages of infected individuals with abnormal electrocardiograms (GII) were 50% for population M and 10% for population T. Many individuals from both populations had measureable IgG2, IgG3 and IgG4 antibodies to FIV, but the level and frequency (%) of positive sera in population T was considerably higher than in population M (70% vs 15% for IgG2; 75% vs 40% for IgG3; 85% vs 20% for IgG4). The level and frequency of IgG1 reactivity against FIV were similar in the two populations. When the sera were titrated, the most remarkable difference in isotype levels between populations T and M was seen for IgG2 and IgG4, the T population showing the highest titer. No association between clinical state and a particular isotype profile was found by ELISA in any population. When the antigen specificity of antibody response was determined by immunoblot, the antigen patterns recognized by sera from the two clinical groups showed some differences only in population M. All sera assayed from GII of population M fixed more IgG than those with normal electrocardiograms (GI). Two bands of 36 and 43 kD were revealed only in GII of this population. Similar antigenic patterns between the two clinical groups from population T were observed, and they were comparable with those obtained with GI from population M.

Animals↗
PubMed1994

Development of high potency universal DR-restricted helper epitopes by modification of high affinity DR-blocking peptides.

Pan DR-binding peptides engineered by introducing anchor residues for different DR motifs within a polyalanine backbone bound 10 of 10 DR molecules tested, with affinities, in most cases, in the nanomolar range. Because of the small methyl group exposed for T cell recognition, these peptides were poor immunogens but effective blockers of DR-restricted antigen presentation. Introduction of bulky and charged residues at positions accessible for T cell recognition yielded extremely powerful Pan DR epitope peptides (PADRE). These peptides elicited powerful responses in vitro from human peripheral blood mononuclear cells (PBMC). Because these cells also cross-react on certain mouse class II alleles, we could also demonstrate that PADRE peptides are active in vivo. In one example of their capacity to elicit T help, they were approximately 1000 times more powerful than natural T cell epitopes. We propose that PADRE peptides may be useful in the development of subunit vaccines.

Alleles↗
PubMed1993

Fine restriction analysis and inhibition of antigen recognition in HLA-DQ-restricted T cells by major histocompatibility complex blockers and T cell receptor antagonists.

The role of polymorphic residues of the beta chain of human histocompatibility leukocyte antigen-DQw5/w6 in antigen presentation to a hepatitis B surface antigen-specific T cell clone was studied. The results obtained demonstrate that the residue situated at position 57 of the beta chain (a valine) is critical for presentation of antigen by antigen-presenting cells to the DQ-restricted T cell clone. Experiments were also done to study the feasibility of peptide blocking of antigen recognition by DQ-restricted T cells. The results indicate that peptides known to associate with DQ molecules are capable of blocking the presentation of antigen to the DQ-restricted T cell clone, presumably by competing with antigen for binding to major histocompatibility complex (MHC) molecules. Moreover, truncations of the stimulatory antigenic peptide resulted in the production of T cell receptor antagonists, which inhibited the response of the T cells to antigen at 10-100-fold lower concentrations than conventional MHC blockers. The role of DQ-restricted T cell responses and peptide blocking approaches in autoimmunity are discussed.

Amino Acid Sequence↗
PubMed1992

Transient accumulation and subsequent rapid loss of messenger RNA encoding high molecular mass CD45 isoforms after T cell activation.

High molecular mass isoforms of CD45 protein tyrosine phosphatase, predominantly CD45RA, are expressed on naive T cells with increasing density during the first 2 days of cellular activation, and subsequently down-regulated concurrent with increasing expression of the low Mr isoform, CD45RO. We show this to be de novo synthesis of CD45RA dependent upon both RNA and protein synthesis. Using a probe shown to detect mRNA encoding the alternatively spliced abc, ab, bc, and b exon isoforms of CD45, the expression of CD45 was analyzed. Kinetic studies of the transition from high to low Mr CD45 mRNA indicate an immediate decrease in the level of high Mr CD45 mRNA after mitogen stimulation of T cells, quickly followed at 4 h by an increase to above steady state levels. This is consistent with the transitory increase in cell-surface density of CD45RA observed at 1 to 2 days poststimulation. Within 24 h of stimulation the level of high Mr CD45 mRNA declines precipitously such that little or no mRNA encoding any of the alternatively spliced exons is detectable. High levels of CD45 mRNA are detectable at later points but this does not hybridize with the Sfa N1 probe recognizing the abc exons suggesting that only the CD45RO mRNA splicing pattern is operative. We also show that CD45 mRNA have a relatively short t1/2. In mitogen-stimulated cells the t1/2 of high and low m.w. CD45 mRNA was estimated at 2.25 h and 3.5 h, respectively. In unstimulated T cells the t1/2 of high Mr CD45 mRNA was estimated at 2.8 h. CD45 mRNA is super-induced in the presence of the protein synthesis inhibitor, cycloheximide, indicating that the degradation and/or splicing of CD45 mRNA is controlled by a labile pathway, and suggesting that mechanisms may exist in vivo to prolong synthesis of CD45RA. The kinetics of accumulation for high Mr CD45 mRNA are very similar to those of the TCR beta-chain and pp56lck suggesting that these functionally linked signaling molecules are regulated in tandem. This implicates stringent molecular control mechanisms on the production of mRNA encoding either high or low m.w. isoforms, consistent with the fundamental role of CD45 in signal transduction, and the apparent need to selectively and sequentially express functionally distinct external CD45 domains.

Antigens, CD↗
PubMed1989

Abnormalities in lymphocyte profile and specificity repertoire of patients with Waldenstrom's macroglobulinemia, multiple myeloma, and IgM monoclonal gammopathy of undetermined significance.

The characteristics of T and B lymphocyte profile and B lymphocyte specificity repertoire were compared in patients with Waldenstrom's macroglobulinemia (WM), IgM monoclonal gammopathy of undetermined significance (IgM MGUS), multiple myeloma (MM), and age-matched normal subjects. Patients with MM had both significantly reduced frequency and number of sIg+ (surface Ig) B cells, whereas patients with WM and IgM MGUS had a reduced frequency but normal numbers of sIg+ B cells in circulation as detected in a capping assay. WM was distinguished by the large numbers of cells in the peripheral blood lymphocyte (PBL) pool that expressed CD9 (BA-2) and CD24 (BA-1) and were monoclonal, based on light chain analysis using flow cytometry. The profile of T lineage cells showed that the ratio of CD4:CD8 was significantly reduced in both MM and WM due to a reduction in the CD4 set. The CD4+ cells were qualitatively abnormal as well, with an enriched proportion of the 4B4+ (CDw29) subset and decreased proportion of the Lp220+ (CD45R) subset. This appeared to be an effect of the disease process on the relatively immature Lp220+ set. From clonal analysis, those patients with WM or IgM MGUS (unlike MM patients) did not exhibit enhanced reactivity with auto-Ig determinants, and most WM patients (7/8) and half of the IgM MGUS patients (3/6) did not have enriched proportions of B cells reactive to tetanus toxoid (TT). The TT-specific B cells in both WM and IgM MGUS, in contrast to MM, appeared fully functional in secretion of anti-TT IgM in vivo. We speculate that the more severe immunodeficiency in MM may be controlled or exacerbated by the presence of an anti-Ig network. The absence of this network in WM allows a relatively more effective immune response, but the immunodeficiency that is observed in these patients involves some abnormality in normal lymphocyte differentiation (is also present in MM).

Antibody Formation↗
PubMed1989

Comparative analysis of immunodeficiency in patients with monoclonal gammopathy of undetermined significance and patients with untreated multiple myeloma.

The objectives of this study were firstly, to compare the immunophenotype of patients with monoclonal gammopathy of undetermined significance (MGUS) with that of patients with newly diagnosed, untreated multiple myeloma (Unt. MM). Our second objective was to determine which variables might distinguish patients with MGUS and early MM. The CD4/CD8 ratio in both patient groups differed significantly from normal as a result of a decrease in the proportion of CD4+ cells. Similarly, surface immunoglobulin-positive (Ig+) B cells were significantly reduced in both groups. Also, some impairment of Ig secretion was observed. An in vitro specificity study of B cells showed an enriched proportion of B cells specific for tetanus toxoid (which may be indicative of enrichment for memory B cells) in both MGUS and Unt. MM patients. Further to this, in MM patients but not in MGUS patients, there was an enriched proportion of B cells specific for determinants on the F(ab')2 fragment of Ig. This suggests an anomalous auto-immune reactivity to polyclonal Ig molecules. In one of the two patients studied, who progressed from MGUS to MM, disease progression was accompanied by an increase in this anti-Ig reactivity. In both patients there was a decrease in CD4/CD8 ratio.

Aged↗
PubMed1988

Loss of CD45R (Lp220) represents a post-thymic T cell differentiation event.

CD45R+ and CDw29+ CD4+ T cells are widely regarded as separate functionally defined T cell lineages. The work described here indicates that they represent maturation stages within the same differentiation pathway. Purified populations of CD4+ or CD8+ T cells, after stimulation with PHA, lose cell surface expression of CD45R (Lp220) and gain an increased surface density of CDw29 (4B4). Clonal analysis demonstrated that individual CD4+ CD45R+ T cells lost CD45R and acquired CDw29 with time in culture. This effect was selective for the high Mr 220-kDa form of the T200 (CD45) complex because the density of CD45, detected by an antibody to common determinants, did not decrease. This strongly indicates that CD45R+ cells are an immature stage in a lineage that culminates in CDw29 expression. To further define the expression of CD45R and CDw29, we analyzed infant thymus cells. Thymocytes include only 4 to 6% CD45R+ cells, but 95% express CDw29 in moderate density. The CD45R+ set appears to include mainly single CD4+ or CD8+, CD3 "bright" medullary cells, although only 15 to 25% of thymocytes with medullary phenotype express CD45R. In vitro culture of thymocytes with Con A and T cell growth factor induces expression of CD45R but these cells differ from the peripheral CD45R+ set by virtue of their co-expression of a high density of CDw29 (4B4) Ag. We postulate that post-thymically CD45R (Lp200) and CDw29 (4B4) comprise a functional assembly on the surface of T cells that changes in composition after stimulation with Ag or mitogen. This may result in enhanced ability of an Ag-experienced T cell to respond effectively to Ag due perhaps to a more efficient signaling complex.

Antigens, Differentiation↗
PubMed1988

Selective loss of CD4+ CD45R+ T cells in peripheral blood of multiple myeloma patients.

The phenotypic distribution of T-lymphocyte subsets in peripheral blood from multiple myeloma (MM) patients shows a reduced proportion of CD4+ cells and a normal proportion of CD8+ cells. The decrease in CD4+ cells could be due to a random process, with all types of CD4+ cells being equally affected, or it could reflect a nonrandom process with selected subsets preferentially reduced. In order to distinguish between these possibilities, double immunofluorescence analysis was performed on blood samples from patients with MM, patients with monoclonal gammopathy of unknown significance (MGUS), and age-matched normal donors, using monoclonal anti-CD4 or anti-CD8 paired with antibodies to the common leukocyte marker Lp220 (CD45R) or 4B4 (CDw29). Normal peripheral blood lymphocytes (PBL) include two phenotypically and functionally distinct CD4+-cell subsets, identified as CD4+ Lp220+ 4B4- and CD4+ Lp220-4B4+, whereas the majority of CD8+ cells expresses Lp220 (70-85%). MM patients had a highly significant selective reduction of the CD4+ Lp220+ subset compared with normal controls (P less than 0.001). Although the percentage of CD4+ Lp220- cells was also reduced in some MM patients relative to normal donors, most of MM patients had an elevated Lp220-/Lp220+ ratio of CD4+ cells (P less than 0.001). The proportion of the two CD8+ subsets was also markedly abnormal. In the set of patients studied the abnormalities within the CD4+ and CD8+ lymphocytes were exclusive to patients with MM since patients with MGUS had normal proportion of CD4+ and CD8+ subsets.

Aged↗
PubMed1988

Apparent loss of 2H4+ T cells in peripheral blood lymphocytes of normal donors: a 2H4-specific artefact unique to T cells.

The antigenic cluster designated CD45R is recognized by a family of monoclonal antibodies. However, one of those most frequently used because of its commercial availability is 2H4. In a series of experiments we show that 2H4 immunofluorescence is almost completely lost from CD4+ or CD8+ T cells of human origin if they are fixed after staining with 2H4. Loss of fluorescence intensity of the total population of 2H4+ lymphocytes and nearly complete quantitative loss of CD45R+ T cells is observed after fixation. This apparent loss of CD45R as detected by 2H4 is not seen if other CD45R-specific monoclonal antibodies are used. Fixation of B cells previously stained with 2H4 gives rise to slightly diminished fluorescence intensity, but no reduction in number of 2H4+ B cells. This appears to be due to a lower antigen density on T cells as compared to B cells. The effect is unique to 2H4, as other monoclonal antibodies recognizing CD45R, while exhibiting a decrease in fluorescence intensity after fixation, still unequivocally detect CD45R+ CD4+ or CD8+ T cells. The effect is restricted to human T cells, as primate lymphocytes, fixed after staining with 2H4, show no loss in fluorescence intensity. We conclude that if it is necessary to fix human T cells after fluorescent staining, the use of CD45R-specific antibodies other than 2H4 is mandatory.

Adult↗
PubMed1984

Study of HLA system in a Mataco population: a geographically isolated American Indian tribe.

A search for antigens of the HLA system has been carried out in 53 Mataco Indians of Argentina living in a geographically isolated area in the northeast of the country. Samples were mostly collected from adults of both sexes who were not directly related. Lymphocyte typing was performed using the microcytotoxicity technique of NIH. 118 sera specific for 15 antigens of the first HLA locus, 22 antigens of the second and 6 of the third were used. The most frequently found alleles were HLA-A28, Aw31 and A2 for the first locus; B15 and B40 for the second; and Cw3 and Cw4 for the third. In addition to previously published investigations on South American Indians, our typing work shows a remarkable homogeneous gene pool and a restricted range of polymorphism; therefore, a further set of haplotypes rendered us also restricted. The most frequent haplotypes that showed a significant statistical linkage disequilibrium were: A2-Cw4, A28-Bx, A2-Cw3, Aw31-Bw16, Aw24-Cw3, B15-Cw3, Bw16-Cw3 and A28-B5. Some of these haplotypes have also been found in other indian populations.

Adult↗
PubMed1984

Study of autoimmune response to rat male accessory glands in rats born to immune mothers.

Passive transfer of antibody across the placenta or in milk has been thought to have a regulatory effect on the immune responsiveness of young animals. The effect of maternal antibody against rat male accessory glands (MRAG) on the systemic autoimmune responses of rat kits was studied. Serum obtained during the nursing period from female rats immunized with 5 mg/0.5 ml of MRAG or human serum albumin (HSA) emulsified in Freund's complete adjuvant before and during pregnancy contained anti-MRAG or anti-HSA, respectively. Kits born to MRAG-immunized dams were intradermally immunized with 5 mg/0.5 ml of MRAG-CFA at 21 and 51 days of age. Control kits from dams immunized with 5 mg/0.5 ml of human serum albumin emulsified in Freund's complete adjuvant (HSA-FCA) were similarly immunized with MRAG-FCA. Delayed-type hypersensitivity (DTH) studied 13 days after immunization with MRAG given at 21 days of age was significantly reduced only in the male kits born to MRAG-immunized dams compared with that of male kits from HSA-immunized dams (P less than 0.005). This hyporesponsiveness was not found in female kits from dams immunized with MRAG-FCA. The titre of circulating anti-MRAG studied at 65 days of age in kits born to MRAG-immunized dams approximated that in control kits. Antibodies against MRAG passively acquired from MRAG-immunized mothers did not alter the humoral autoimmune response of their kits.

Animals↗
PubMed1983

Evaluation of the immunosuppression in an experimental model of autoimmunity: suppressor activity of spleen cells from cyclophosphamide-treated rats.

Rats immunized with chemically modified rat male accessory glands (MRAG) and injected 3 days later with cyclophosphamide (CY) were unable to develop humoral and cellular immune response to the autoantigen of MRAG. The present report demonstrates that the spleen mononuclear (SpM) cells transference from rats injected with CY 3 days after the antigen to normal male or female syngeneic animals before immunization with MRAG did not suppress the immune response to this antigen, whereas the transference of SpM cells from suppressed animals to animals previously immunized, depressed the delayed type hypersensitivity (DTH) response against MRAG (suppression of the expression) only in male rats. Similar results were obtained by transference of purified T cells. SpM cells did not suppress an established humoral immune response induced in male or female rats. The results suggest that non-adherent cells present in the spleen of male suppressed rats might be one of the responsible mechanisms for suppression of the efferent phase of the cellular autoimmune response to MRAG.

Animals↗