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Biomedical subjects

L Hammarström

Publications and source records attributed to L Hammarström.

At least 235 records · Page 13Linked to original sources
PubMed1988

The antibody spectrum in individuals with defect expression of HLA class II and the LFA-1 glycoprotein family genes.

HLA class II antigens and the LFA-1 (lymphocyte function-associated type 1) glycoprotein family are cell surface structures of central importance in many lymphocyte reactions. Specific antibodies are normally restricted to particular IgG subclasses. In order to study the mechanism of isotype restriction we have analysed specific IgG1, IgG2, IgG3 and IgG4 antibodies directed against a number of different protein and polysaccharide antigens in individuals with HLA class II or LFA-1 deficiency. HLA class II deficiency resulted in decreased total IgG2, IgG4 and IgA in 4/4 patients, whereas total IgM and IgG were low in 2/4. In HLA class II deficiency the levels of specific antibodies directed against protein as well as polysaccharide antigens were frequently low. Virtually normal total as well as specific antibody levels were found in individuals with both severe and moderate forms of LFA-1 deficiency. There was no clear evidence for an abnormal subclass pattern of specific antibodies with a shift from one subclass to an isotype which is normally not used, in any of the patient groups investigated.

Adult↗
PubMed1988

A time-related study of healing in the marginal periodontal/root interface.

Healing in a marginal periodontal wound was followed from 1 to 56 days with scanning electron and light microscopy. It was shown that early cell reactions on the root surface involves a plaque-induced inflammation with an apical migration of marginal epithelium, thus preventing connective tissue attachment. New cementum was found only on old cementum in the most apical part of the experimental wound. A temporal morphological baseline was established for further studies on the influence of various local endogenous and exogenous factors on marginal periodontal healing.

Alveolar Process↗
PubMed1988

Subclass distribution and IgE responses after treatment in human schistosomiasis.

The IgG and IgA subclass distribution of specific antibodies as well as the distribution of total and specific IgE in 15 patients with schistosomiasis was determined in consecutive samples before and after initiation of treatment. An adult worm antigen preparation and a soluble egg antigen preparation were used as antigens in the ELISA assays. After initiation of treatment a rise was noted in certain subclasses and a correlation was found for specific IgG1 and IgG4 serum levels in the egg-excreting patients against adult worm antigen and for specific IgG4 and IgE levels in sera from the eight patients with a chronic disease. They also had a rise of the specific IgA1 titre and six of them also of specific IgA2. Members of eosinophilic granulocytes reached a peak after 2 weeks in seven of the eight patients. The increase of eosinophils was an early event as opposed to the incidence of peak of the determined specific isotypes. The associated rise in IgG1, IgG4 and IgE antibody concentrations and eosinophils may suggest a causal relation possibly induced by common interleukins.

Adolescent↗
PubMed1988

The sequential appearance of IgG subclasses and IgE during the course of Trichinella spiralis infection.

Earlier studies have shown that IgG1 and IgG4 are the dominant IgG subclasses in the specific response during a chronic helminthic infection. It has also been suggested that IgG4 production results from chronic or repetitive antigenic stimulation and a correlation between IgG4 and IgE levels exists. An outbreak of Trichinella spiralis infection in Poland provided the opportunity to follow the sequential appearance of the IgG subclass and IgE responses in 15 patients during the early stage of Trichinella infection and to compare these observations in sera obtained one year later from the same patients. The results show that the sequential appearance of the IgG subclasses were IgG1 before IgG3 and IgG3 before IgG4. IgG1 antibodies dominated the immune response in all patients. A statistically significant increase in the number of IgG4 positive sera was observed in patients during the chronic stage compared to the findings during the early stage of infection (13% vs 73%; p less than 0.001), supporting the view that IgG4 results from a chronic antigenic stimulation. A correlation between the appearance of IgG4 and IgE was not found. The highest levels of IgE were seen in the first serum samples obtained, with a decrease during the course of infection.

Adolescent↗
PubMed1987

The use of human antigen-specific monoclonal antibodies in an enzyme-linked immunosorbent assay for the determination of anti-HBsAg antibody subclasses.

A human monoclonal anti-HBsAg antibody (IgG1, lambda) was used as a reference for an ELISA determination of the serum levels of anti-HBsAg antibodies in human volunteers after vaccination with H-B vax. The IgG subclass distribution of specific antibodies showed a marked dominance of IgG1 antibodies. In addition, small amounts of specific IgG4 antibodies were occasionally found, suggesting a different pattern from that found after natural disease. The novel use of a human monoclonal antibody to measure specific antibodies may give a more accurate determination of specific IgG subclass levels than previously available methods.

Antibodies, Monoclonal↗
PubMed1987

Human T-cell tumours containing chromosome 14 inversion or translocation with breakpoints proximal to immunoglobulin joining regions at 14q32.

T-cell tumours are frequently found to carry an inversion of chromosome 14 (inv(14)) (q11;q32) or more rarely a chromosome 14 translocation t(14;14) with the same cytogenetic breakpoints (q11;q32). We have examined the molecular junctions of an inv(14) and a translocation t(14;14) using T-cell receptor (TCR) alpha joining (J) region probes. Both of these chromosomal abnormalities have breakpoints within the TCR J alpha locus at 14q11 and both have breakpoints which are proximal (i.e. on the centromeric side) to the immunoglobulin heavy chain JH region at 14q32. The cloned segments corresponding to the junctions at 14q32 are not associated with obvious immunoglobulin-like sequences. This contrasts to the previously described inv(14) in the cell line SUP-T1 and places a potential cluster of chromosome 14 breakpoints downstream of the Ig JH locus. The possible role of the varying breakpoints in the development of these tumours is discussed.

Amino Acid Sequence↗
PubMed1987

Immunoglobulin prophylaxis in patients with antibody deficiency syndromes and anti-IgA antibodies.

Sera from three hundred five patients with immunoglobulin deficiencies were analyzed for the presence of anti-IgA antibodies by using indirect agglutination and enzyme-linked immunosorbent assay (ELISA). Anti-IgA antibodies were observed in 15 of 68 (22%) patients with hypogammaglobulinemia and 53 of 185 (29%) patients with selective IgA deficiency, both groups having serum IgA less than 0.05 g/liter. The highest frequency, 6 of 10 or 60%, was noted for patients with a combined IgA-IgG2 deficiency. No anti-IgA antibodies were detected in 25 patients with serum IgA between 0.05 and 0.27 g/liter and normal amounts of serum IgM and IgG or in 17 patients with hypogammaglobulinemia who had serum IgA of 0.05-0.7 g/liter. The anti-IgA antibodies were primarily of the IgG class, but IgD and IgM anti-IgA were occasionally found. IgE anti-IgA antibodies could not be detected with the presently used technique. The IgG anti-IgA antibodies were mainly of the IgG1 subclass but occasionally also of the subclasses IgG2, IgG3, and IgG4. Of eight patients with anti-IgA antibodies, seven tolerated Ig prophylaxis with a commercial immunoglobulin preparation low in IgA when given either intramuscularly or intravenously. The titers of anti-IgA in the sera of these patients did not rise in relation to the prophylaxis. Only one of the eight patients had a history of previous anaphylactic reactions to IgA-containing blood products. He tolerated six Ig infusions during 5 months with the IgA-depleted preparation without any adverse effects but showed increasing levels of anti-IgA antibodies and ultimately experienced a near-fatal reaction at the seventh infusion.

Antibodies, Anti-Idiotypic↗
PubMed1987

Subclass restriction pattern of antigen-specific antibodies in donors with defective expression of IgG or IgA subclass heavy chain constant region genes.

We have developed a method for the measurement of the IgG and IgA subclass distribution of antigen-specific human antibodies. The controls for the specificity of the assay include the use of a number of monoclonal human antibodies and sera from individuals with deletions of particular immunoglobulin heavy chain constant region genes. The system was used to determine the shift in immunoglobulin subclass patterns of specific antibodies against a variety of protein and polysaccharide antigens in individuals with a regulatory deficiency of a given IgG or IgA subclass. Normally, the pattern is quite distinct and antibodies against protein antigens are mainly of the IgG1 subclass, whereas antibodies against polysaccharide antigens are mainly of the IgG2 subclass. The results on serum from an IgG1 deficient donor suggested that IgG3 and IgG4 appear to compensate for a lack of IgG1, whereas isolated deficiencies of IgG3, IgG4, or IgA2 do not markedly influence the expected distribution of specific antibodies. In IgG2-deficient individuals a more complex pattern was observed where antibodies against protein antigens were retained, whereas levels of antibodies against polysaccharide antigens could vary markedly between donors, which appeared to be dependent on whether the IgG2 deficiency was an isolated defect or combined with IgG4/IgA deficiency. However, all the IgG2-deficient donors had a skewed pattern of anti-polysaccharide antibodies with a shift to IgG1 to IgG3.

Antibodies↗
PubMed1987

Generation of the antibody repertoire in individuals with multiple immunoglobulin heavy chain constant region gene deletions.

Antibodies against protein antigens are largely restricted to the IgG1 subclass in man, whereas anti-carbohydrate antibodies, at least in adults, are almost exclusively confined to the IgG2 subclass. In IgG2-deficient donors where the C gamma 2 gene is retained in the genome, antibodies against most polysaccharide antigens are absent. We therefore undertook a study of the antibody repertoire in 11 adult donors with immunoglobulin heavy chain constant region gene deletions, homozygous or heterozygous defects, encompassing the C gamma 2 gene. In all cases, antibodies against polysaccharide antigens were present and restricted to the remaining subclasses (IgG1 and/or IgG3). These results suggest an unrestricted use of the available VH gene repertoire in donors lacking the C gamma 2 gene, and imply that the limited antibody repertoire found in IgG2-deficient individuals with a retained C gamma 2 gene may be a consequence of an altered regulatory mechanism or a structural VH gene defect. However, furthermore, the deletion of multiple C gamma heavy chain constant region genes did not appear to decrease the IgG switch probability as such, since total serum levels of IgG appear to be normal.

Antibody Formation↗
PubMed1987

Immunoglobulin subclass distribution of specific antibodies in allergic patients. Prediction of the IgE inducing capacity of potential allergens.

The IgG and IgA subclass distribution of specific antibodies against a variety of protein and polysaccharide antigens was determined in sera from individuals with high levels of IgE. No shift of the antibody pattern could be observed, suggesting that the aberrant regulation of responses against allergens noted in these patients is limited, encompassing selected antigens only. Antibodies against protein antigens are mainly of the IgG1 subclass. In addition, low levels of specific IgG3 or IgG4 antibodies may be formed. Our data suggest that a given antigen induces either IgG3 or IgG4 and that potential allergens, in addition to IgG1 and IgE, elicit a response restricted to IgG4.

Antibodies, Anti-Idiotypic↗
PubMed1987

New attachment in monkeys with experimental periodontitis with and without removal of the cementum.

Experimental periodontitis was induced in monkeys by means of elastic orthodontic ligatures. The periodontally-involved teeth were then treated with different methods. At the end of the treatment period, the monkeys were sacrificed. The premolar-molar areas were dissected out and embedded in a low-viscosity embedding medium (Spurr). The results of the treatment procedures were analyzed on ground sections. Formation of new cementum and new bone was determined by means of tetracycline labeling. Root planing with an ultrasonic device or with hand instruments almost completely removed the cementum and a portion of the peripheral dentin. The root surface was more uneven after treatment with the ultrasonic device than after using hand instruments. No new attachment could be found after root planing. Cleaning of the periodontally-involved root surfaces with two detergents (cetylpyrimidinium chloride and sodium-N-lauroyl sarcosine) without root planing resulted in a significant amount of new attachment.

Animals↗
PubMed1987

Comparative effects of parathyroid hormone on osteoblasts and cementoblasts.

Although bone, dentin and dental cementum are mesenchymal mineralized tissues composed mainly of collagen and hydroxy apatite, they differ markedly in their suceptibility to resorption. Bone undergoes physiological resorption to which the dental tissues appear to be resistant. Recently, the cells covering bone surfaces have been attributed a regulatory role in osteoclastic bone resorption by exposing the bone surface following stimulation with hormones and inflammatory mediators, thereby allowing osteoclasts to colonize the bone surface. In the present study, it was shown that reparative cementum-forming cells covering an experimental cavity in the root surface of replanted monkey incisors were unaffected by parathyroid hormone, a potent mediator of bone resorption. In parallel experiments, endocranial osteoblasts exposed bone surface by widening their inercellular spaces. It was concluded that the layer of cells covering the root surface forms a protective barrier against resorption which serves to preserve the integrity of the dental root.

Animals↗
PubMed1987

Cellular colonization of denuded root surfaces in vivo: cell morphology in dentin resorption and cementum repair.

Cellular colonization of denuded root surfaces on replanted teeth was examined with scanning electron microscopy. The dentin surface was rapidly colonized by a few macrophage-like cells which resorbed dentin in limited areas. They had well-developed ruffled borders but no clear zones. The resorptive activity was gradually inhibited by the ingrowth of a monolayer of fibroblast-like cells from the periphery of the denuded area. At the advancing front, the ingrowing fibroblast-like cells were long and slender, with long tail-like projections trailing the nuclear domain. The invading cells behind these were well-spread and tightly packed. They had a granulated surface and showed morphological signs of fibre synthesis. After 6 weeks, the entire cavity was covered by a monolayer of these cells. Removal of the cells with sodium hypochlorite revealed that a cementum-like tissue had been formed under the invading cells, indicating that they were cementoblasts. It was concluded that wound repair on the root surface is dependent upon the differentiation and proliferation of pre-cementoblasts in the periphery of the wound and that cells in the main body of the periodontal membrane are of little significance in the healing process on the root surface.

Animals↗
PubMed1987

B-cell chronic lymphocytic leukaemia with aberrant expression of CD8 antigen.

The monoclonal antibodies against CD8 (T suppressor/cytotoxic) antigen (Leu2/OKT8) were found to bind to leukaemic lymphocytes from a patient with chronic lymphocytic leukaemia. The cells also had an unusual type of rod-like cytoplasmic immunoglobulin of IgM/lambda type as seen by light, fluorescence and electron microscopy, and displayed several antigens characteristic for B lymphocytes. Gene rearrangement analysis showed rearrangement of mu heavy chain gene. In spite of an expression of CD8 antigen, T-cell receptor genes were not rearranged.

Aged↗