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Biomedical subjects

R Wistar

Publications and source records attributed to R Wistar.

At least 19 recordsLinked to original sources
PubMed1991

Use of adjuvant containing mycobacterial cell-wall skeleton, monophosphoryl lipid A, and squalane in malaria circumsporozoite protein vaccine.

Human immune responses to modern synthetic and recombinant peptide vaccines administered with the standard adjuvant, aluminum hydroxide, tend to be poor, hence the search for better adjuvants. Antibody responses to a Plasmodium falciparum circumsporozoite (CS) protein vaccine, R32NS1(81), administered with an adjuvant containing cell-wall skeleton of mycobacteria and monophosphoryl lipid A in squalane (MPL/CWS) have been compared to responses to the same immunogen administered with aluminum hydroxide. 2 weeks after the third dose the following indices were greater in the 5 patients who received MPL/CWS than in controls (p less than 0.05): the geometric mean concentration (2.0 vs 25.4 microgram/ml) and avidity index of antibodies to the P falciparum CS protein by ELISA, the geometric mean titre to P falciparum sporozoites by IFAT (1/115 vs 1/1600), and the geometric mean inhibition of sporozoite invasion of hepatoma cells in vitro (37.6 vs 90.3%). For R32NS1(81) MPL/CWS is superior to aluminum hydroxide as an adjuvant, and the data support the evaluation of this complex as an adjuvant for other vaccines.

Adjuvants, Immunologic↗
PubMed1988

Mucosal and systemic immunity to Campylobacter jejuni in rabbits after gastric inoculation.

The mucosal and systemic immune responses to Campylobacter jejuni were studied in rabbits receiving gastric inoculation with live organisms. A lavage procedure was used to facilitate repeated monitoring of the intestinal immune response to C. jejuni. Immunity to C. jejuni was determined by secondary challenge by using the removable intestinal tie adult rabbit diarrhea (RITARD) model and monitoring for resistance to colonization and bacteremia. Oral-gastric inoculation of normal rabbits produced a transient intestinal colonization without diarrhea. C. jejuni serotypes differed in their ability to colonize the intestines of rabbits and to stimulate primary intestinal and serum antibody responses. Animals previously colonized were resistant to recolonization and the development of bacteremia after homologous challenge by the RITARD procedure but were not resistant to heterologous challenges. Anticampylobacter intestinal and serum IgA titers before this secondary infection were the most reliable predictors of resistance to colonization and bacteremia.

Animals↗
PubMed1988

Immune response of humans to the circumsporozoite protein of Plasmodium falciparum: limited T cell response to the immunodominant central repeat region.

Most adults in highly malarious areas have antibodies to the repeat region of the circumsporozoite protein of Plasmodium falciparum. To determine if a T cell epitope on the repeat region stimulated T cell help for this antibody, we used R32tet32, a recombinant construct derived from the repeat region of the circumsporozoite protein of P. falciparum, to stimulate in vitro mononuclear cells from residents of an area hyperendemic for malaria. Three groups differing in the length of time they had resided in a malarious area were studied. The percentage of individuals in each group who had positive antibody responses to R32tet32 increased with increased exposure to malaria. However, antibody positivity was not correlated with in vitro lymphocyte proliferation responses to the antigen. Lymphocytes from 79% of the individuals showing serum antibodies to R32tet32 failed to respond in a lymphocyte transformation assay, suggesting that T cell helper activity in these individuals was based upon the recognition of a T cell epitope not located within this peptide.

Animals↗
PubMed1987

Gastric lavage: a simple method to obtain IgA-rich intestinal secretions from the rabbit.

A lavage procedure was developed to obtain intestinal secretions from rabbits. The procedure facilitated the repeated monitoring of the intestinal IgA immune response of these animals to enteric infection with Campylobacter jejuni. This non-invasive technique was easily performed, reproducible and yielded consistent levels of IgA from rabbit intestinal secretions. It is anticipated that this procedure will aid in the study of the intestinal immune response of rabbits to other enteric pathogens.

Animals↗
PubMed1987

Differential reactivity of rheumatoid synovial cells and serum rheumatoid factors to human immunoglobulin G subclasses 1 and 3 and their CH3 domains in rheumatoid arthritis.

19S IgM rheumatoid factors (RF) are polyclonal autoantibodies that may play an important pathogenic role in sustaining inflammatory synovitis in rheumatoid arthritis (RA). RF in RA have reactivity for as-yet-uncharacterized antigenic determinants in IgG Fc. We hypothesized that qualitative differences might exist between some of these RF molecules, and that differences such as reactivity and affinity might characterize more pathogenic RF molecules. Previous observations in our laboratory indicate that RF produced by rheumatoid synovial cells (RSC) have greater reactivity with human IgG and IgG3 subclass, in contrast to serum RF, which has greater reactivity with rabbit IgG and human IgG1. These observations were made using a complement-dependent RF plaque-forming cell assay. The purpose of this study was to validate and extend those observations. Therefore, we examined the reactivity of RSC and serum RF with human and rabbit IgG and the reactivity and avidity of RSC-RF for IgG1 and IgG3 molecules and Fab, F(ab')2, and pFc' fragments thereof in a solid-phase enzyme immunoassay. In particular, we found: RSC-RF had at least twice as much reactivity with human IgG as with rabbit IgG; serum RF had approximately equal reactivity with human and rabbit IgG; RSC-RF had greater reactivity and avidity for IgG3 and IgG3 pFc' than for IgG1; and RSC-RF was nonreactive with Fab or F(ab')2 from either IgG1 or IgG3. These results suggest that the major antigenic determinant for RSC-RF resides in the CH3 domain of the IgG3 molecule. Precise characterization of this epitope may provide further insight into the etiology and pathogenesis of RA.

Arthritis, Rheumatoid↗
PubMed1987

Humoral immune function in severe, active rheumatoid arthritis.

Peripheral blood mononuclear cells (PBMC) from 30 patients with definite or classic active rheumatoid arthritis who were on no remittive drugs were studied for spontaneous and pokeweed mitogen (PWM)-stimulated immunoglobulin plaque-forming cell frequency (IgPFC), spontaneous IgM-rheumatoid factor (IgM-RF) secretion, and in vitro proliferative responses to soluble recall antigens. Rheumatoid spontaneous total (IgG + IgM + IgA) IgPFCs were higher than those of normal controls when assayed after 7 days in culture. Spontaneous and PWM-stimulated IgM-PFCs, in contrast, were significantly less than normal regardless of when assayed. Spontaneous synthesis of IgM-RF was observed in 56% of the RA patients, but absolute amounts produced were widely heterogeneous. Spontaneous IgM-RF production by RA PBMC was associated with low or absent spontaneous IgM-PFC production. Moreover, a strong association was found between the median amount of IgM-RF secreted and depressed proliferative responses to soluble recall antigens. Our results define several abnormalities of immunoglobulin production in a clinically homogeneous and highly active rheumatoid population and delineate methodologic variations that can complicate the interpretation of similar data in the literature. In addition, our findings suggest that subgroups of rheumatoid patients that show distinct cellular and humoral immune abnormalities can be identified.

Adult↗
PubMed1987

A new protocol to digest human IgM with papain that results in homogeneous Fab preparations that can be routinely crystallized.

A method has been developed for the routine production of Fab fragments from human IgM in high yield. After the IgM is purified at physiological pH, it is digested with papain in the presence of cysteine at room temperature for 16 hours. The Fab fragments are purified initially by gel filtration and then by ion exchange chromatography. The yield of Fab has been 60-80%. Some heterogeneity in the size of the Fabs from the different monoclonal IgMs has been observed. Fab fragments from four different IgM rheumatoid factors (RF) have been crystallized after such digestion and purification, in a variety of conditions including phosphate buffer alone or with the precipitating agents ammonium sulfate, polyethylene glycol or methylpentanediol. This modified papain digestion method has also been used for another non-RF monoclonal human IgM with equally good yield. Biological activity can be detected in the purified Fab fragment indicating that this procedure does not destroy the native conformation of the molecule.

Amino Acid Sequence↗
PubMed1986

Use of monoclonal antibodies to quantify subclasses of human IgG. I. Development of two-site immunoenzymometric assays for total IgG subclass determinations.

Dissection of the IgG antibody response into its subclass components has been difficult largely because of the lack of adequate supplies of specific reagents. The development of monoclonal antibodies (Mcab) promises to overcome this problem, but the use of such antibodies has certain inherent problems. It has been shown recently that Mcabs which were avid, potent and specific for well defined epitopes may partially or completely lose their activity depending on the assay system in which they were used. In order to identify Mcabs that would be specific and useful as capture antibodies in a simple two-site enzymometric assay, a panel of 18 Mcabs was screened and one Mcab to each of the four IgG subclasses was identified for quantitation of subclass levels in human serum.

Antibodies, Monoclonal↗
PubMed1986

Immunity to malaria and naturally acquired antibodies to the circumsporozoite protein of Plasmodium falciparum.

A candidate Plasmodium falciparum sporozoite vaccine, R32tet32, which includes 32 tetrapeptide repeats derived from the circumsporozoite protein of P. falciparum, has been developed on the basis of the hypothesis that antibodies to the repeat region of this protein will protect against sporozoite infection. The results of two in vitro assays, the circumsporozoite precipitation reaction and the inhibition of sporozoite invasion into hepatoma cells, are thought to indicate protective immunity. We therefore tested serum samples from persons living in a hyperendemic malarious area of Indonesia for antibodies against R32tet32 and for their ability to produce circumsporozoite precipitation and to inhibit sporozoite invasion of hepatoma cells. The prevalence and mean titer of antibody against R32tet32 increased with the age of the subjects, whereas the prevalence of P. falciparum infection in the community decreased. Only serum samples with IgG or IgM R32tet32 antibody titers greater than or equal to 1/800 had precipitation activity and invasion-inhibiting activity of more than 75 percent. When the serum samples were fractionated by affinity chromatography, only the fractions containing purified human antibody to R32tet32 were found to contain this activity. These data support the hypotheses that antibodies to the circumsporozoite protein are important in reducing the prevalence of malaria with increasing age among persons in areas in which malaria is endemic and that vaccine-elicited antibody to the circumsporozoite repeat region will protect against infection with P. falciparum sporozoites.

Adolescent↗
PubMed1986

Estimation of the relative avidity of 19S IgM rheumatoid factor secreted by rheumatoid synovial cells for human IgG subclasses.

19S IgM rheumatoid factors (RF) may play an important role in sustaining inflammation in rheumatoid arthritis (RA). As yet, no unique antigenic specificity for RF in RA has been identified. Because the synovium is central to the pathogenic changes in RA, RF produced therein might be pathogenically more important than serum RF. Therefore, we examined the reactivity and relative avidity of 19S IgM-RF in serum and rheumatoid synovial cells (RSC) from 20 patients with seropositive RA. Reactivities were determined by competitive inhibition of serum RF hemolytic activity and RSC RF-plaque-forming cells (PFC) by added soluble antigen, i.e., monomeric human IgG subclasses. Estimation of relative avidities of RSC RF for human IgG subclasses was done by calculation of fractional RF expression in the RSC RF-PFC assay following inhibition by IgG subclasses. RSC RF had greatest reactivity with IgG3 and IgG1, some reactivity with IgG2, and the least reactivity with IgG4. Serum RF reacted most with IgG1 and IgG2, reacted some with IgG4, but reacted poorly with IgG3. The antigenic determinants with which RSC RF reacted were common to many IgG3 molecules. The highest relative avidity of RSC RF was for IgG3. These observations indicate a selective deficiency of serum RF compared with RSC RF and suggest an important pathogenic role for these qualitatively different RSC RF molecules for in situ RF immune complex-mediated inflammation in RA synovial tissue.

Animals↗
PubMed1985

Sequence of the immunodominant epitope for the surface protein on sporozoites of Plasmodium vivax.

Plasmodium vivax is one of the four malaria parasites that cause disease in humans. The structure of the immunodominant repeating peptide of the circumsporozoite (CS) protein of P. vivax was determined. A fragment of P. vivax DNA that encodes this tandemly repeating epitope was isolated by use of an oligonucleotide probe whose sequence is thought to be conserved in CS protein genes. DNA sequence analysis of the P. vivax clone indicates that the CS repeat is nine amino acids in length (Gly-Asp-Arg-Ala-Asp-Gly-Gln-Pro-Ala). The structure of the repeating region was confirmed with synthetic peptides and monoclonal antibodies directed against P. vivax sporozoites. This information should allow synthesis of a vaccine for P. vivax that is similar to the one being tested for P. falciparum.

Amino Acid Sequence↗
PubMed1985

Comparative specificities of serum and synovial cell 19S IgM rheumatoid factors in rheumatoid arthritis.

Rheumatoid factor (RF) may play a role in sustaining the inflammatory events and tissue damage in rheumatoid arthritis (RA). However, many serum RF have greater specificity for rabbit IgG than for human IgG, thus raising questions about RF pathogenicity in RA. Serum RF also has specificity for human IgG subclasses 1, 2 and 4, but not for IgG3. The synovium is central to the pathology of RA; thus, RF made there may have greater pathogenicity than serum RF. We examined the specificity of 19S IgM RF in an RF plaque forming cell assay (RF-PFC) using RA synovial cells (RSC). We found that: (1) RSC produced greater numbers of RF-PFC/10(6) cells than did RA peripheral blood mononuclear cells (PBM); (2) RSC RF-PFC had greater specificity for human than for rabbit IgG compared to autologous serum RF; (3) RSC RF had significantly greater specificity for human IgG3 relative to autologous serum RF. In contrast, RSC RF and autologous serum RF had the same relative specificities for polyclonal human IgG, IgG1, IgG2, and IgG4. Thus, the specificity of much of the RF synthesized by RSC differed from serum RF. The potential pathogenic significance of these observations is discussed.

Animals↗
PubMed1984

Time-varying magnetic fields: effect on DNA synthesis.

Human fibroblasts have exhibited enhanced DNA synthesis when exposed to sinusoidally varying magnetic fields for a wide range of frequencies (15 hertz to 4 kilohertz) and amplitudes (2.3 X 10(-6) to 5.6 X 10(-4) tesla). This effect, which is at maximum during the middle of the S phase of the cell cycle, appears to be independent of the time derivative of the magnetic field, suggesting an underlying mechanism other than Faraday's law. The threshold is estimated to be between 0.5 X 10(-5) and 2.5 X 10(-5) tesla per second. These results bring into question the allegedly specific magnetic wave shapes now used in therapeutic devices for bone nonunion. The range of magnetic field amplitudes tested encompass the geomagnetic field, suggesting the possibility of mutagenic interactions directly arising from short-term changes in the earth's field.

Cells, Cultured↗
PubMed1982

Activation of human platelets by antibodies to thymocytes and beta 2-microglobulin. II. Effect of purified beta 2m on the platelet aggregating and lymphocytotoxic activities of HATG and SA beta 2mG.

Platelet aggregating (PAA) and lymphocytotoxic activities (LTA) of antibody preparations known to have immunosuppressive properties were studied in this work. In comparison to sheep anti-human beta-2-microglobulin globulin (SA beta 2mG), horse anti-human thymocyte globulin (HATG) was about twice as potent by weight in LTA than in PAA, suggesting that a considerable portion of antibodies in HATG had been generated against lymphocyte specific antigens. Evidence is presented that not only the LTA but also the PAA is a direct effect of both HATG and SA beta 2mG on lymphocytes and platelets. The specificity of the antibodies was investigated by means of purified human urinary beta-2-microglobulin (beta 2m). Beta-2-microglobulin had no detectable inhibitory effect on the LTA and, in most cases, on the PAA of HATG. Even in a highly sensitive assay system, no more than 5 to 7% of the total PAA of HATG was inhibitable by beta 2m. In contrast, both the PAA and LTA of SA beta 2mG could be inhibited by beta 2m in a time- and dose-dependent fashion. The results prove that HATG and SA beta 2mG exert their actions through different membrane components on both platelets and lymphocytes. This is consistent with our earlier observation that the PAA of HATG and SA beta 2mG may widely dissociate among various human platelet-rich plasmas. Relatively low response to anti-beta 2m in the presence of high reactivity to ALG/ATG can also be explained by varying plasma levels of beta 2m. Finally, inhibition of the PAA of SA beta 2mG by purified beta 2m provides the first model where the platelet aggregating effect on an inducer (anti-beta 2m) can quantitatively be blocked by its specific "solubilized" receptor (beta 2m) whose structure is fully understood.

Animals↗
PubMed1982

Activation of human platelets by antibodies to thymocytes and beta 2-microglobulin. III. Effect of cell absorptions on the platelet aggregating and lymphocytotoxic activities of HATG and SA beta 2mG.

Horse anti-human thymocyte globulin (HATG) and sheep anti-human beta-2-microglobulin globulin (SA beta 2-mG), both known to have immunosuppressive potency, were quantitatively absorbed by a number of human cells, then, tested for platelet aggregating and lymphocytotoxic reactivities. Peripheral blood lymphocytes, lymphoblastoid T- and B-cell lines, platelets and spermatozoa could remove varying amounts of both reactivities from HATG and SA beta 2mG. Daudi cells were effective in reducing the lymphocyte and some platelet reactivity of HATG but did not affect those of SA beta 2mG. Erythrocytes had no absorption capacity for either antibody. The qualitative and quantitative differences in absorbing with various cells on the platelet aggregating and lymphotoxic activities of HATG and SA beta 2mG indicate the high specificity and direct action of the antibodies on platelets and lymphocytes.

Absorption↗
PubMed1982

A mitogen for human B cells: anti-Ig coupled to polyacrylamide beads activates blood mononuclear cells independently of T cells.

The F(ab')2 fragment of rabbit anti-human F(ab')2 antibodies covalently linked to polyacrylamide beads (anti-Ig beads) acts as a polyclonal mitogen for human B cells in whole peripheral blood mononuclear cells (PBM) or tonsil cells. Activation, measured by the rate of DNA synthesis, is the result of an interaction between the anti-Ig beads and membrane immunoglobulin found on B cells. Excess soluble human F(ab')2 blocks activation with anti-Ig beads. Immunospecifically purified antibodies against IgM or IgD bound to beads activate lymphocytes. Also soluble anti-IgM or anti-IgD can block activation with insolubilized anti-IgM or anti-IgD, respectively, by modulating membrane immunoglobulin. Irrelevant rabbit antihapten antibodies bound to beads failed to activate PBM or tonsil cells. Anti-Ig beads act independently of T cells. The anti-Ig beads lead to activation of B cells without further maturation to polyclonal immunoglobulin secretion.

Acrylic Resins↗
PubMed1980

Effect of immunoglobulin G on the responsiveness of human neutrophils to soluble staphylococcal protein A-induced neutrophil migration inhibition factor from T-lymphocytes.

Staphylococcal protein A is a bacterial cell wall product that binds human immunoglobulin G and thereby interferes with opsonization and phagocytosis of Staphylococcus aureus by neutrophils. Phagocytic cells are also responsive to various non-immunoglobulin lymphocyte mediators. We utilized the detection of a newly recognized mediator, a neutrophil migration inhibition factor from T-lymphocytes (NIF-T), to show that aggregates of staphylococcal protein A and immunoglobulins G could inhibit the responsiveness of neutrophils to NIF-T. That such aggregates may alter the responsiveness of neutrophils to lymphocyte mediators that amplify or modulate phagocytic functions may have important pathogenetic implications in staphylococcal infection.

Cells, Cultured↗