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Biomedical subjects

J G Tew

Publications and source records attributed to J G Tew.

At least 127 records · Page 7Linked to original sources
PubMed1982

Relationship between attachment loss and precipitating serum antibody to Actinobacillus actinomycetemcomitans in adolescents and young adults having severe periodontal destruction.

The purpose of this study was to determine if adolescents and young adults with severe periodontal disease had precipitating serum antibody reactive with Actinobacillus actinomycetemcomitans, and, if so, to correlate presence or absence of the precipitin with clinical patterns of periodontal destruction. Double diffusion in gel was used to detect precipitins. Test and known positive standard sera were run in different wells against a common well containing a minute of sonicates from two strains of A. actinomycetemcomitans (Y4 and N27). Periodontal loss of attachment was measured with a probe on four surfaces per tooth; missing and unerupted teeth were noted with the aid of radiographs. Precipitating antibody was seen in 77% of sera from 22 subjects with localized juvenile periodontitis, 40% of 35 young subjects with more generalized severe disease, and 2% of 44 periodontally healthy individuals. About 80% of the positive reactions were with strain Y4. Within the diseased groups, there were significantly fewer involved teeth in subjects with precipitating antibody (Ab+) than among those in whose sera precipitins were not seen (Ab-). Comparisons of the distribution and severity of involved teeth between Ab+ and Ab- subjects were consistent with an hypothesis that high levels of antibody specific for A. actinomycetemcomitans have a protective effect against periodontal destruction.

Actinobacillus↗
PubMed1982

Blastogenic responses by lymphocytes from periodontally healthy populations induced by periodontitis-associated bacteria.

Studies of blastogenic responsiveness induced in peripheral blood lymphocytes (PBL) from periodontally healthy subjects by periodontal bacteria have conflicted. This study was undertaken to examine the blastogenic response of periodontally healthy subjects under experimental conditions which provide improved control of laboratory variables. By using cryopreserved PBL the responses of all subjects in an experiment were determined on the same day under identical conditions. The periodontally healthy populations consisted of subjects of the same age range and sex matched to three distinct groups of periodontally diseased subjects (i.e., juvenile (JP), severe (SP), and moderate (MP) periodontitis). The bacterial stimulants tested were chosen on the basis of known association with and isolation from persons fitting the disease classifications. If PBL response differences between periodontally healthy and diseased subjects exist they should be most obvious in response to predominant organisms associated with the disease states. PBL cultures were harvested after a 4 hour pulse with 3H-thymidine on days 4 and 6 of culture. Three separate experiments were conducted comparing one healthy group and one diseased group. In all three experiments subjects in the healthy group responded as frequently as did those in the diseased group, the dose-response distribution was indistinguishable, and the magnitude of the responses was not substantially different between groups. These results suggest nonspecific activation as the major determinant in the blastogenic response, rather than specific sensitization occurring during initiation or progression of periodontitis.

Adolescent↗
PubMed1981

The maintenance of B-cell and T-cell function in frozen and stored human lymphocytes.

The objective of this study was to identify and test a convenient means for long-term storage of lymphocytes taken from clinically characterized patients without losing B- or T-cell function. Accordingly, peripheral blood lymphocytes were frozen and stored, and portions of each sample were subsequently assayed for T-cell blastogenic response and B-cell Jerne plaquing at various time intervals after freezing. A comparison of the cell counts of fresh and frozen cultures indicated that cell were recovered after freezing. Furthermore, these cells showed no significant differences in (i) cell viability; (ii) blastogenic response to antigens of Actinomyces maeslandii, Bacteroides melaninogenicus, Fusobacterium nucleatum, and tetanus toxoid; (iii) blastogenic response to phytohemagglutinin and pokeweed mitogen; and (iv) polyclonal B-cell response to pokeweed mitogen as measured by the direct Jerne plaque assay. The retained blastogenic and plaquing responses seen in frozen cultures indicated the maintenance of both T-cell and B-cell function, respectively. This is the first reported demonstration of Jerne plaquing of normal human lymphocytes after freezing. It appears that freezing techniques provide a means for repeating and extending both T- and B-cell assays using frozen stored portions of the same cell samples.

Antibody-Producing Cells↗
PubMed1981

Polyclonal B-cell activation induced by extracts of Gram-negative bacteria isolated from periodontally diseased sites.

The objective of this research was to determine whether gram-negative bacteria frequently isolated from periodontally diseased sites contained polyclonal B-cell activators. Polyclonal B-cell activation, which results in nonspecific activation of multiple B-cell clones was analyzed by a hemolysis-in-gel assay designed to detect a broad range of antibody specificities. Extracts from numerous bacterial strains, including Bacteroides gingivalis, Bacteroides melaninogenicus subsp. melaninogenicus, B. melaninogenicus subsp. intermedius, Fusobacterium nucleatum, Selenomonas sputigena, Capnocytophaga ochracea, and Actinobacillus actinomycetemcomitans, were tested. Extracts of the above organisms were found to stimulate polyclonal antibody responses in cultures of normal human peripheral blood lymphocytes, although the magnitude of stimulation varied among the extracts. Optimal antibody-forming cell responses were found at stimulator doses between 5 and 1,000 micrograms/ml. We conclude that the resident gram-negative subgingival flora associated with periodontal lesions possesses potent polyclonal B-cell activators. These activators may contribute to disease pathogenesis by inducing B lymphocytes to produce antibody, osteolytic factors, or both and possibly other mediators of inflammation.

Actinobacillus↗
PubMed1981

Long-term antigen retention by dendritic cells in the popliteal lymph node of immunized mice.

Antigen retention by follicular dendritic cells (FDC) was studied in the popliteal lymph nodes (PLN) of mice actively or passively immunized against human serum albumin (HSA) or horse spleen ferritin. Electron microscopic autoradiography was used to locate a challenge dose (1 microgram) of 125I-labelled HSA in the draining PLN following injection into the hind footpad of specifically immune mice. In both actively and passively immunized mice, the radiolabelled antigen was localized to the follicles in the cortex of the draining node. In actively immunized mice, the antigen formed a crescent of label on the superficial aspect of germinal centres, while in passively immunized mice label was seen in primary follicles. In electron microscope autoradiographs, the silver grains were concentrated in areas of dendritic cell processes which emanated from a cell body containing a characteristic irregular nucleus. The size and complexity of the dendritic cell processes increased in actively immunized mice suggesting that the FDC could hypertrophy. High resolution studies using the electron-dense antigen, ferritin, showed that it was localized to the extracellular space of the FDC processes and was associated with amorphous electron-dense material; presumably immune complexes. Antigen was not present uniformly distributed in the extracellular material but rather it was in discrete patches occupying small segments of the FDC processes. Large amounts of label-free electron-dense material were present suggesting that immune complexes of various specificities were present on each DC. Ferritin was seen more than 3 months after challenge but only on the FDC. The data suggest that the antigen retaining mechanism in the lymph node of immune mice is antigen non-specific, is capable of hypertrophy in response to active immunization and provides a mechanism for stable long-term retention of antigen.

Animals↗
PubMed1980

Immune elimination and immune retention: the relationship between antigen retained in the foot and the elicitation of footpad swelling.

We determined whether (1) long term antigen retention is present in distal sites after footpad challenge of immune mice; (2) if antigen retained in the foot is selectively localized; and (3) if the foot is adversely affected by the retained antigen. Mice immune or non-immune to human serum albumin (HSA) were injected in the hind footpads with 125I-HSA. In immune mice rapid clearance of radiolabel occurred in the liver, lungs, kidney, blood and urine but radiolabel was retained in the hind feet, draining lymph nodes and spleen. Non-immune mice rapidly cleared radiolabel from these sites. Autoradiography revealed that most of the radiolabel in the feet was in flexor tendons and tendon sheaths. Electron microscope autoradiography indicated that antigen was associated with collagen at the tendon surface, but not with cells or cell processes. Radiolabel solubilized from the feet, lymph nodes and spleen could be specifically precipitated with rabbit anti-HSA. Histological examination of the tendon and surrounding tissues did not show that retained antigen was causing inflammation or chronic tissue damage. Nanogram levels of antigen could elicit swelling in the sensitized foot even if the antigen was injected at a remote site, but mice immunized by other routes or against other antigens did not show footpad swelling. Antigen retained on collagenous tissues may induce hypersensitivity and thus play a role in rheumatic diseases.

Animals↗
PubMed1980

Antibody isotypes mediating antigen retention in passively immunized mice.

Antibody isotypes vary in their capacity to mediate retention of a readily catabolized protein antigen, human serum albumin (HSA) in spleen, popliteal lymph node (PLN) and hind foot. Hyperimmune anti-HSA mouse sera were separated into fractions highly enriched for IgM, IgG1 and IgG2 via differential elution from protein A-Sepharose. These fractions were used to immunize normal mice passively. Twenty-four hours later the mice were injected with radio-iodinated HSA into the hind footpad. When the amount of HSA retained in the spleen 6 days later was determined, the potency of various antibody fractions to mediate retention could be ranked IgG2=IgG1 > IgM. The amount of HSA retention mediated by various fractions correlated well with autoradiographic evidence demonstrating localization of HSA in splenic follicles. The localization pattern in PLN was similar to the spleen except that the IgM-containing fraction mediated follicular localization of HSA to a considerable degree. In tendons of the hind foot, IgG1 mediated HSA retention five times better than IgG2 or IgM fractions. The amount of radioactivity found in the liver varied inversely with HSA retention in other locations. The results demonstrate differences in antibody isotype requirements for antigen localization in spleen, regional lymph node and collagenous sites of the hind foot.

Animals↗