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Biomedical subjects

T E Michaelsen

Publications and source records attributed to T E Michaelsen.

18 recordsLinked to original sources
PubMed1979

High-density lipoprotein as carrier for amyloid-related protein SAA in rabbit serum.

In this study present evidence that SAA is complexed to high density lipoprotein (HDL) in rabbit serum and is co-isolated with HDL apoproteins. The binding of SAA to HDL seems to be quite strong, judged from affinity chromatography experiments. The studies did not reveal any interaction between SAA and albumin, and there was no evidence that SAA could complex to itself. By isolation of HDL apoproteins, SAA seems to behave like other known apoproteins and may be characterized as an apoprotein that is present in normal serum in very low concentration but increases in concentration under different unphysiological circumstances.

Amyloid↗
PubMed1979

Lack of suppressor cell activity in rheumatoid synovial lymphocytes.

Lymphocytes were eluted from the synovial tissue of seventeen patients with rheumatoid arthritis (RA) and one with ankylosing spondylitis. In eight of these patients immunoglobulin production by synovial lymphocytes in the presence and absence of pokeweed mitogen was studied. In nine patients T lymphocytes were isolated from the eluted cells, and the T helper and suppressor cell functions were evaluated in an allogeneic co-culture system. Peripheral blood lymphocytes (PBL) from twenty-eight normal donors were also studied for comparison. Immunoglobulin produced by synovial lymphocytes was higher than in PBL of normal donors. However, the stimulation index of synovial tissue lymphocytes was lower. Most of the normal donors had suppressor cell activity in their peripheral blood, whereas in synovial tissue lymphocytes a statistically significant number of patients did not have any suppressor cell activity. In contrast, the synovial tissue lymphocytes showed helper activity not differing significantly from that of the T lymphocytes from peripheral blood of normal individuals.

Adolescent↗
PubMed1979

Demonstration of rheumatoid factor idiotypic antigens on peripheral blood B and T lymphocytes from patients with rheumatoid arthritis.

Antisera were raised against three polyclonal IgM rheumatoid factors (RF). After adequate absorptions, the antisera were rendered idiotype-specific, as assayed by haemagglutination technique. By using the anti-idiotype antisera in indirect immunofluorescence on peripheral blood lymphocytes from the patients used as donors for the immunizing RF, it was demonstrated that 3-14% of the lymphocytes were stained, and thus had membrane-bound structures with idiotypic antigens similar to those of the circulating IgM RF of the same patients. While most of these idiotype-positive lymphocyte were B lymphocytes, it was demonstrated in one patient that about 7% of the T lymphocytes also had the same idiotypic antigens.

Arthritis, Rheumatoid↗
PubMed1979

Mitogenic stimulation of human lymphocyte subpopulations by Lathyrus odoratus lectin.

Investigation was made of the mitogenic activation by Lathyrus odoratus (LATH) lectin and phytohaemagglutinin (PHA) of human T-enriched and non-T lympohcytes isolated by nylon wool filtration and sheep erythrocyte rosette depletion, respectively. LATH stimulated only weakly the T-enriched and non-T fractions as compared to PHA which strongly stimulated the T-enriched population and weakly stimulated the non-T cells. Removal of phagocytic cells from the unfractionated lymphocytes caused only a slight reduction in the response to LATH. The responses of mixtures of T-enriched and non-T lymphocytes were similar to that of unfractionated lymphocytes. The LATH lectin seems, therefore, to be neither a pure T nor a pure non-T cell mitogen, since both populations must be present for optimal response. When alpha-methyl-D-mannoside was added to unfractionated lymphocytes together with LATH, there was a strong inhibition of thymidine incorporation. D-glucose and N-acetyl-D-glucosamine diminished the stimulation effect to a lesser degree.

Cells, Cultured↗
PubMed1979

Shared idiotypes of human peripheral blood B and T lymphocytes.

In a patient with an IgG lambda monoclonal serum component possessing anti-streptolysin O activity, we have demonstrated peripheral blood B and T lymphocytes with shared or similar idiotypes. The idiotypic T lymphocyte membrane structure was capable of binding the specific antigen (SLO). After radioiodination and subsequent detergent solubilization of the same T cell population, immunoprecipitation of the lysate by employing anti-idiotypic antibodies, resulted in the isolation of a polypeptide chain with a m.w. of 70,000 on SDS polyacrylamide gels under reducing conditions. The polypeptide expressed no isotypic immunoglobulin markers. Internal labeling experiments indicated that this membrane structure was actively synthesized by the T lymphocytes.

Antigens↗
PubMed1977

Primary structure of the "hinge" region of human IgG3. Probable quadruplication of a 15-amino acid residue basic unit.

The middle part of the heavy chain of IgG3 (hinge region) which covalently links the two gamma3 chains to each other, is about 4 times larger than the same region in the three other human IgG subclasses. This is probably due to a quadruplication of a 45-nucleotide DNA segment resulting in a gamma3 hinge region which is 62 amino acid residues long and consists of an NH2-terminal 17-residue segment followed by a 15-residue segment which is identically and consecutively repeated three times. The NH2-terminal 17-residue segment shows 70% homology with the repetitive 15-residue segment and appears to be the result of a small insertion and several point mutations of the same 45-nucleotide DNA stretch. Since this unit of repetition shows 60 to 70% homology with the hinge of the other IgG subclasses, it may represent the primitive IgG hinge.

Amino Acid Sequence↗
PubMed1977

Cross-idiotypic reactions among anti-Rh (D) antibodies.

In a series of experiments several idiotype-specific rabbit antisera produced against different IgG anti-Rh (D) antibodies reacted with other anti-Rh (D) antibodies and thus showed cross-idiotypic reactions. Some of the antisera agglutinated almost all types of anti-D-sensitized erythrocytes, whereas other idiotype-specific antisera agglutinated only a few anti-D-sensitized erythrocytes. Anti-D-antibodies showed several different cross-idiotypic reaction patterns. The cross-idiotypic antigens were, in most instances, localized to the heavy chains only. In a few cases, however, the cross-idiotypic antigens were dependent on the interaction between heavy and light chains.

Cross Reactions↗
PubMed1977

Identification and characterization of different amyloid fibril proteins in tissue sections.

Antisera specific for 4 different classes of amyloid fibril proteins, amyloid protein AA and the immunoglobulin light-chain amyloid proteins AlambdaI, AlambdaIV, and AlambdaV, were used to identify these proteins directly in tissue sections from 25 patients with amyloidosis. The specificity of these reactions was established by blocking experiments with purified amyloid fibril proteins and Bence Jones proteins of known variable subgroups. Protein AA was detected in 17 patients, including all 13 with secondary amyloidosis, 2 with primary amyloidosis and 2 with Waldenström's macroglobulinemia. Immunoglobulin light-chain proteins AlambdaI, AlambdaIV, and AlambdaV were in 3, 1, and 2 patients, respectively, all of whom had primary or myeloma/macroglobulinemia-associated amyloidosis. Antiserum specific for the amyloid-related serum protein SAA reacted with the same tissues as anti-AA and had the same pattern of staining in tissue sections.

Amyloid↗
PubMed1977

A high molecular weight serum protein is the carrier for amyloid-related protein SAA.

In the present study evidence is presented that SAA in serum complexes to a carrier protein with a molecular weight of 100,000-200,000 daltons, with mobility in the alpha-region on electrophoresis, and with a rather low normal serum concentration. The carrier protein is apparently not albumin. SAA isolated from the carrier protein has a molecular weight of 14,000 daltons and does not complex to any considerable extent with itself under neutral conditions.

Amyloid↗
PubMed1977

Complement activation and phagocytosis of cryoglobulin particles in a patient with plasma cell proliferative disease.

The serum of a patient with a non-aggressive plasma cell proliferative disorder contained two monoclonal immunoglobulins: IgG3 lambda in moderate concentration and having cryoglobulin features, and IgA kappa in low concentration and without cryoprecipitability. The patient's serum had low complement concentration and C3 was partly converted into split products in vivo. Complement (C3) together with cryoglobulin and fibrinogen was found by immunofluorescence in sections from skin showing vasculitis. The cryoglobulin particles which formed at room temp. were vividly phagocytized in vitro by neutrophile granulocytes from the patient and from normal individuals as demonstrated in light microscopy and ultramicroscopy.

Biopsy↗
PubMed1977

A study of the variable heavy chain (VH) region of membrane-bound Ig on human chronic leukemic lymphocytes.

Lymphocytes from 20 patients with chronic lymphocytic leukemia (CLL) were studied for membrane staining by direct immunofluorescence by employing anti-F(ab')2, anti-VHI, anti-VHII, anti-VHIII subgroup-specific antisera, as well as light chain-specific antisera. Some lymphocyte preparations were also studied in indirect immunofluorescence with an antiserum raised against a fragment (VH) corresponding to the variable region of the heavy chain of a human IgG3 myeloma protein (Kup). Lymphocytes from each CLL patient demonstrated a restriction of VH subgroups expressed on the cell membrane; six were restricted to the VHI subgroup, seven to VHII, and seven to the VHIII subgroup. This restriction gave further evidence for monoclonality of the membrane-bound Ig and the leukemic cell proliferation. Antiserum to the VH fragment stained closely similar percentages of CLL lymphocytes to that obtained with anti-F(ab')2 antiserum. Furthermore, double staining revealed that the same cells were stained with anti-VH antiserum as were stained with anti-F(ab')2 antiserum, i.e., only the B lymphocytes.

Adult↗
PubMed1977

The amino acid sequence of a human immunoglobulin G3m(g) pFc' fragment.

Amino acid sequence analysis of the pFc' fragment obtained by pepsin digestion of an IgG3; G3m(g) human myeloma protein HER shows it to consist of 112 residues. It starts at position 334 (gamma1 numbering), contains eight residues of the Cgamma2 region, and the whole Cgamma3 domain. Comparison with the sequence of gamma1 shows five differences including an extra Met at 397. Each is accountable by a single base substitution. The sequence is identical to that of a G3m(b0) molecule except for the previously noted allotype related Tyr/Phe exchange at position 436. The high degree of homology (95%) among gamma-chain subclasses suggests a recent diversification.

Amino Acid Sequence↗
PubMed1977

Antigenic studies of a VH fragment: demonstration of three sets of antigens, idiotypic, VH subgroup, and VH framework-specific antigens.

The antigenic properties of the VH region of immunoglobulin heavy chains were studied by means of a fragment corresponding to the variable part of the heavy chain of an IgG3 myeloma protein (KUP) and an antiserum made against this fragment. By hemagglutination, hemagglutination inhibition, and immunofluorescence techniques, it was shown that the anti-VH antiserum detected three sets of antigens in the VH region, namely idiotypic antigens, VH subgroup-specific antigens, and VH domain-(framework) specific antigens. The VH fragment inhibited in a VHII subgroup-specific hemagglutination inhibition test system. The VH fragment was thus antigenically similar to the tvh region found in the intact molecules and the light chains were not needed to express the VH subgroup antigens or the VH framework antigens.

Alkylation↗
PubMed1976

Indications that the Cgamma2 homology region is not a regular domain.

The Cgamma2 homology region of rabbit IgG does not behave like a domain. Thus, there is no trans-interaction between the two Cgamma2 regions; instead there is an unusual cis-interaction between Cgamma2 and Cgamma3 regions. The observations were made on the plasmin digestion products Facb (IgG minus the Cgamma3 region) and pFc' (Cgamma3 region), which did not dissociate under neutral conditions but dissociated in 3M guanidine solution (that is, cis-interaction between Cgamma2 and Cgamma3). The Facb fragment split into subunits with equal molecular weights under neutral conditions on partial reduction and alkylation (that is, lack of trans-interaction between the two Cgamma2 in the molecule).

Animals↗
PubMed1976

Restriction of human immune antibodies to heavy-chain variable subgroups.

Human immune antibodies such as anti-Rh and anti-Kell antibodies were tested in hemagglutination and hemagglutination inhibition experiments for VH subgroup composition. A striking VH subgroup restriction was found in several of these groups of antibodies. In the majority of cases there was a restriction to one particular VH subgroup for a single antibody specificity in a given individual. In some cases there was also an overall restriction to one particular subgroup for antibodies with the same antibody specificity. This was particularly pronounced for anti-D antibodies, which was primarily restricted to VHII, and for the anti-Kell, which was particularly related to VHIII. Subgroup-specific antigens for all the main VH subgroups were blocked on combination of the antibody molecule with antigen. No relation was found between VH restriction and restriction to IgG subclass, or genetic markers or chi and lambda light-chain type.

Antibodies↗
PubMed1975

Structural requirements in the Fc region of rabbit IgG antibodies necessary to induce cytotoxicity by human lymphocytes.

Rabbit IgG anti-chicken erythrocyte antibodies were compared with the Fab/c or Facb fragments of IgG and with partially reduced and alkylated IgG for the capacity to induce cytotoxicity by normal human lymphocytes. The Fab/c antibody fragment, which lacks one Fab region, was still able to induce cytotoxicity. In contrast, the Facb antibody fragment, which lacks the C-gamma3 domains, was nearly ineffective in activating the effector cells, whereas intact antibody activity was demonstrated by its ability to inhibit the cytotoxicity induced by unsplit IgG. Similarly, partial reduction and alkylation of the IgG antibodies, under conditions affecting the interchain disulphide bonds only, greatly diminished their ability to induce cytotoxicity, although they effectively inhibited the cytotoxicity induced by untreated IgG. On the basis of these results and previous data, we suggest that the reaction of the Fc region of IgG with the effector cell depends on the integrity of the C-gamma2 domain in the native, divalent state or on the interaction between the C-gamma2 and C-gamma3 domains.

Alkylation↗
PubMed1975

Isolation and characterization of amyloid-related serum protein SAA as a low molecular weight protein.

With direct immunoprecipitation or gel filtration under dissociating conditions, amyloid-related serum protein SAA has been isolated as a low molecular weight protein from the serum of two patients with rheumatoid arthritis but without known amyloidosis. The isolated protein SAA showed antigenic identity and an amino acid composition that was similar, but not identical, with isolated fibril protein AA. Molecular weight estimations suggest that protein SAA is approximately 50% larger than protein AA and has a molecular weight of 14,000-15,000 daltons. Preliminary results indicate that protein SAA from a patient with amyloidosis has a similar small molecular weight subunit.

Adolescent↗