Biomedical subjects

M Teodorescu

Publications and source records attributed to M Teodorescu.

At least 19 recordsLinked to original sources

PubMed2001

Anti-topoisomerase I (anti-Scl-70) antibodies in patients with systemic lupus erythematosus.

OBJECTIVE: To investigate the presence and clinical significance of anti-Scl-70 antibodies in patients with systemic lupus erythematosus (SLE). METHODS: Levels of antibodies against Scl-70 were determined by a commercial clinical enzyme-linked immunosorbent assay (ELISA) during routine evaluation. Results were verified by an additional ELISA with a characterized bovine Scl-70, by ELISA with a recombinant human topoisomerase I, by Western blot, and by double diffusion in agar gel. Disease activity was estimated retrospectively by the Systemic Lupus Activity Measure (SLAM). RESULTS: Of 128 consecutive SLE patients, 25% were positive for anti-Scl-70 antibody; this antibody activity was cognate in nature. No SLE patient could be classified as also having systemic sclerosis. The levels of anti-Scl-70 were significantly correlated with the SLAM score for the entire cohort (r = 0.563, P < 0.001) and for 7 individual patients with multiple longitudinal measurements (r = 0.755-0.951, P < 0.001; n = 6) (r = 0.378, P < 0.05; n = 1). A significant correlation was also found between the levels of anti-Scl-70 and anti-double-stranded DNA antibodies (r = 0.558, P < 0.001). Patients with anti-Scl-70 had significantly higher risk of pulmonary hypertension (P < 0.01) and renal involvement (P < 0.001) than patients without this antibody. CONCLUSION: Anti-Scl-70 antibody is present in a significant subset of patients with SLE. For this subset, it offers a good correlate of disease activity and suggests increased risk for pulmonary hypertension and nephritis.

Autoantibodies↗

PubMed2001

De novo production of IgG antinuclear antibodies in a neonate.

We describe the first case in which de novo production of multiple IgG antinuclear antibodies (ANA) occurred in a female neonate of an ANA negative mother. The infant presented at 4 weeks of age with hemorrhagic panencephalitis, diffuse intraparenchymal hemorrhages, and straight sinus thrombosis. She had been vaccinated against hepatitis B at birth. No other cause was found and maternal prenatal care was unremarkable. The infant's screening ANA test by ELISA was positive at 6 weeks with specificity for ssDNA, Sm, and nRNP/Sm. At 8 weeks antibodies to dsDNA and centromere were detected as well. By 8 months, she still had slightly elevated anti-dsDNA, Sm, and nRNP/Sm antibodies. The ANA test by immunofluorescence was abnormal at 8 weeks through 13 weeks with centromere and then homogeneous pattern. Based on similarities with other reported cases, we speculate that hepatitis B vaccination may have been involved in the development of antinuclear antibodies.

Adult↗

PubMed2000

Noncognate binding to histones of IgG from patients with idiopathic systemic lupus erythematosus.

The mechanism of attachment of circulating immune complexes (CIC) to glomerular basement membranes (GBM) has not yet been elucidated. Since it has been proposed that histone may be the ligand between GBM and DNA/anti-DNA CIC, we explored by ELISA and Western blots the nature of the interaction of IgG with histone on solid phase. Cognate binding of IgG anti-histone antibody was characteristically dependent on in its F(ab')(2) fragment and was inhibited by free histone. On the other hand, heat-aggregated IgG, a model for CIC, and IgG from most patients with idiopathic SLE had a characteristic noncognate binding behavior to histone: it was dependent on Fcgamma rather than on the F(ab')(2) fragment and was not effectively inhibited by free histones. Also, binding to histone of in vitro generated DNA/anti-DNA immune complexes was not dependent on DNA as a histone ligand, but on Fcgamma. Finally, there was good agreement between the binding of this IgG to histone and to C1q. We concluded that: (1) altered IgG and/or CIC bind to solid-phase-attached histone primarily through their Fcgamma and (2) CIC may mimic IgG antihistone antibodies in solid-phase immunoassays.

Antigen-Antibody Complex↗

PubMed2000

Specific binding of IL-8 to rabbit alpha-macroglobulin modulates IL-8 function in the lung.

OBJECTIVE AND DESIGN: The purpose of this study was to compare chemotactic activity of IL-8 alone with that of IL-8 reacted with rabbit alpha-macroglobulins (alphaM) in vivo. METHODS: Initially the binding of recombinant human IL-8 (rhIL-8) to rabbit alphaM was studied. 125I-labeled rhIL-8 was incubated with alphaM, and electrophoresed on native 5% gels or SDS-polyacrylamide 4-20% gradient gels. Next, rhIL-8 or rhIL-8 bound to alphaM was administered via an endotracheal tube to rabbit's lungs. TREATMENT: An endotracheal tube was wedged into a segment of the lobe of each lung, and a sample instilled through the tube into this segment. After 4 h the lungs were lavaged. RESULTS: rhIL-8 bound to alphaM retained its full chemotactic activity in vitro but exhibited a diminished ability to induce the influx of neutrophils into the rabbit lung. CONCLUSIONS: The data suggest that alphaM may facilitate IL-8 clearance from the lung.

Animals↗

PubMed2000

Effect of circulating immune complexes on the binding of rheumatoid factor to histones.

OBJECTIVE: To determine whether the reaction of rheumatoid factor (RF) with solid phase histone is due to the simultaneous presence of circulating immune complexes (CICs) or aggregated IgG. METHODS: Serum samples from 56 patients with seropositive rheumatoid arthritis (RA) and 50 random blood bank donors were used. Binding of immunoglobulins to histone was determined by enzyme linked immunosorbent assay (ELISA) and by western blots. Aggregated IgG was obtained by heating at 61(o)C for 30 minutes. RESULTS: Among the RA sera tested by ELISA, 54% were positive for histone binding by IgM, IgG, or IgA and 20% by IgM only. Heating of normal sera caused a significant enhancement in the binding of IgG to histone (p<0.001). This binding had a non-cognate behaviour-that is, it was destroyed by pepsin treatment of serum and was not significantly inhibited by competition with free histone. The same behaviour was seen for IgM, IgG, and IgA binding from RA sera. However, cognate IgG antibody binding to histone was inhibited by free histone and was resistant to pepsin digestion. Addition of heat aggregated IgG to RA sera or pretreatment of histone with aggregated IgG caused a significant increase in IgM binding to histone. CONCLUSION: IgM, IgG, and IgA RF bind to solid phase histone as a result of attachment to histone of immune complexes or aggregated IgG and not as a result of a cognate reaction with histone.

Antigen-Antibody Complex↗

PubMed2000

Differences in clinical sensitivity of ELISA tests for autoantibodies with human and bovine extractable nuclear antigens.

Bovine antigens are routinely used in indirect ELISA tests to detect autoantibodies against extractable nuclear antigens (ENA). Here we investigate the difference in clinical sensitivity between ELISA tests prepared with native human and bovine antigens. SSA and SSB were obtained from spleen and nRNP/Sm complex from thymus. Each antigen was extracted with the same immunoaffinity column. ELISA tests with human and bovine antigens were set up under the same conditions of clinical specificity established on 50 blood bank donors. Of 109 random SLE and Sjogren's syndrome sera 49% and 35% were positive, respectively, for human and bovine SSA, 26% and 16% for SSB. Of 98 random SLE sera 52% and 41% were positive for human and bovine nRNP/Sm, respectively. A few specimens reacted only with bovine antigens, probably false positive reactions. The relative clinical sensitivity for all specimens identified as positive by human and/or bovine antigens was significantly higher with human than with bovine SSA, (93% vs 67%; P<0.001, chi2), SSB (93% vs 50%; P<0.001), and for nRNP/Sm (96% vs 75%; P<0.01). However, for values that exceeded 2.5-4 times the upper normal limit, the levels were similar for human and bovine antigens. We concluded that native human antigens offer clinical sensitivity superior to native bovine antigens for the measurement of anti-ENA antibodies by ELISA.

Animals↗

PubMed2000

Circulating anticentromere CENP-A and CENP-B antibodies in patients with diffuse and limited systemic sclerosis, systemic lupus erythematosus, and rheumatoid arthritis.

OBJECTIVE: To determine the disease sensitivity and specificity of testing for autoantibodies against 2 of the 3 main human centromere antigenic components, CENP-A and CENP-B (recombinant, expressed in baculovirus). METHODS: ELISA with CENP-A and CENP-B antigens were used to test 45 sera showing a centromere pattern by immunofluorescence (IFA) and sera from 96 patients with systemic sclerosis (SSc), subdivided into diffuse (dSSc) and limited (lSSc) forms. For controls, the same tests were performed on sera from 100 patients with rheumatoid arthritis (RA), 100 with systemic lupus erythematosus (SLE), and 50 random blood donors. Sera from all the patients with SSc were also tested for the presence of anti-Scl70 antibody by ELISA (bovine antigen), and for pattern and titer by IFA (HEp-2 cells). RESULTS: Of the 45 IFA positive sera, 93% were positive for anti-CENP-A and 91% for anti-CENP-B. There was a very good quantitative correlation between the antibody levels against these 2 centromere components (r = 0.597; p<0.001). Anti-CENP-A and B were found in 48% of patients with lSSc, and in 11% and 9%, respectively, of those with dSSc. The difference in the frequency of anti-CENP-A between the 2 patient groups was significant (chi-squared, p<0.001). Similar levels of anticentromere staining pattern by IFA were observed for these 2 groups. Anti-Scl70 was elevated in 8% of lSSc and 25% of dSSc patients; this difference was also significant (chi-squared, p = 0.02). Neither CENP-A nor CENP-B reacted with IgG from SSc patients containing anti-Scl70. The frequency of abnormal levels in patients with SLE and RA was, respectively, 11% and 3% for anti-CENP-A and 4% and 3% for anti-CENP-B. The reaction of IgG from SLE and RA patients with CENP-A was not inhibited by histone H3, i.e., it was not due to recognition of the histone-like domain in CENP-A. Thus, when 96 SSc patients were compared to 200 patients with RA and SLE, the disease specificity of anti-CENP-A and B was 93% and 96.5%, respectively. CONCLUSION: In addition to IFA, ELISA tests for CENP-A and CENP-B yield results with similar sensitivity and specificity for the diagnosis of SSc. CENP-A and CENP-B are primarily associated with lSSc. In SSc the autoantibody response is directed simultaneously and with similar amplitude against these 2 components of the centromere structure, whereas in other autoimmune diseases the response is directed mainly against one of the 2 components.

Adult↗

PubMed1998

High frequency of abnormal levels of IgA anti-beta2-glycoprotein I antibodies in patients with systemic lupus erythematosus: relationship with antiphospholipid syndrome.

OBJECTIVE: To determine the frequency of IgA, in addition to IgM and IgG, anti-beta2-GPI and anticardiolipin (aCL) antibodies in patients with systemic lupus erythematosus (SLE), and to relate the presence of these antibodies to symptoms of antiphospholipid antibody syndrome (APS). METHODS: Sera from 100 blood bank donors (controls) and 48 patients with SLE were tested by ELISA. The same enzyme conjugates were used in the measurement of aCL and anti-beta2-GPI. Medical records were reviewed for the presence of manifestations of APS: arterial occlusion, pulmonary embolism, cerebrovascular accident, transient ischemic attack, venous thrombosis (deep or superficial), hemolytic anemia, thrombocytopenia, repeated fetal loss, leg ulcers, seizures, avascular bone necrosis, cerebritis, or migraine. RESULTS: Above normal levels of antibodies of all 3 isotypes against beta2-GPI were found in 5% of controls and 73% of patients with SLE. Antibodies against cardiolipin in the 2 groups were found in 5 and 37%, respectively. IgA anti-beta2-GPI was found in 2% of controls and 58% of patients with SLE; in contrast, only 2% of patients with SLE had IgA aCL. In the 48 patients studied, thrombosis and fetal loss were present in 10 (Group 1), other manifestations of APS were present in 18 (Group 2), and none in 20 (Group 3). Antibodies to beta2-GPI of all 3 isotypes were found in a higher proportion of APS (Group 1 plus Group 2) (82%) than in Group 3 (50%) (p < 0.01, chi-squared). There was also a significantly higher proportion of patients with elevated anti-beta2-GPI in Group 1 (90%) than in Group 3 (p < 0.02). There was a significantly higher frequency (p < 0.01) and level (p < 0.05) of IgA anti-beta2-GPI in patients with APS than in those with no APS manifestations. Moreover, compared to aCL and with other isotypes of anti-beta2-GPI, the highest antibody levels were observed in IgA antibeta2-GPI. CONCLUSION: The sensitivity of the anti-beta2-GPI antibody test for APS in patients with SLE is significantly increased by measuring IgA, in addition to IgM and IgG isotype.

Adolescent↗

PubMed1997

Routine measurement of IgM, IgG, and IgA rheumatoid factors: high sensitivity, specificity, and predictive value for rheumatoid arthritis.

OBJECTIVE: To determine the isotype specificity and clinical utility of routine testing by ELISA of IgM, IgG, and IgA rheumatoid factors (RF). METHODS: The test was performed on 619 individual specimens: blood bank donors (n = 130); rheumatoid arthritis (RA, n = 139); connective tissue diseases (CTD, n = 71); miscellaneous rheumatic disorders (MRD, n = 91); and 188 consecutive clinical laboratory specimens that tested positive by latex agglutination. Rabbit IgG was used as the antigen attached to the solid phase, and rabbit IgG antibody-enzyme conjugates against IgM (Fc5mu), IgG[F(ab')2], and IgA (alpha chain) were used, respectively, to detect IgM, IgG, and IgA RF. The serum was digested with pepsin to facilitate the measurement of IgG RF. RESULTS: All 3 isotypes were specifically identified; IgM RF was destroyed by pepsin and IgG RF was specifically measured, without interference from IgA RF. Using data obtained from 98 RA specimens and 162 disease controls, the 3 main clinical variables--sensitivity, specificity, and predictive value--were stratified according to 3 combinations of RF isotypes: IgM only (91, 76, and 62%); IgM+IgA (79, 89, and 80%), and IgM+IgG+IgA (53, 99, and 96%). For patients with the 3 isotypes plus > 150 U of IgM and/or IgA the clinical variables were 70, 97, and 93%. In patients with RA the IgG RF was found only in association with IgM RF, i.e., there was no "hidden" RF, and IgA RF was always accompanied by IgM RF. There was a continuous decline in all 3 RF isotypes during treatment with gold salts. The sensitivity of ELISA for IgM RF exceeded that of nephelometry or latex agglutination. CONCLUSION: Routine measurement of IgM, IgG, and IgA RF by ELISA with rabbit IgG as the antigen and pepsin digestion for the detection of IgG RF provides useful information in the differential diagnosis of patients with arthritis.

Antibody Specificity↗

PubMed1990

Clinical value of an integrated ELISA system for the detection of 6 autoantibodies (ssDNA, dsDNA, Sm, RNP/Sm, SSA, and SSB).

An ELISA panel assay (ANA/6) which simultaneously detects IgG autoantibodies against 6 antigens (ssDNA, dsDNA, Sm, RNP/Sm, SSA, and SSB) was evaluated with sera from 98 patients with systemic lupus erythematosus (SLE) and related conditions, 68 disease controls, who were positive or negative by fluorescent ANA (FANA), and 100 healthy controls. The antigen panel specifically identified the particular autoantibodies present and had a high level of sensitivity which was reflected by the frequency of detection of autoantibodies in different patient groups. All active patients with SLE were positive for at least one autoantibody and 80% of these patients had 3 or more autoantibodies compared to only 20% of inactive patients. A large heterogeneity in antibody profiles was also noted. About 90% of patients with positive FANA, but no detectable autoimmune rheumatic disorder, i.e., false positive, were negative by the panel. A new method of standardization was designed to use the ANA/6 quantitatively. Very large differences in the level of all 6 autoantibodies were observed between sera from patients with active and inactive SLE, suggesting a potential usefulness of ANA/6 for patient management.

Antibody Specificity↗

PubMed1989

Covalent binding to alpha-macroglobulins of a protein with free SH groups produced by activated B cells: blocking by D-penicillamine and gold compounds.

alpha 2-Macroglobulin (alpha 2M) complexed with proteinases or modified by the action of amines has been shown to affect immune responses in vitro, though as yet the mechanisms are poorly understood. Supernates from rabbit lymphoid cells cultured in medium with normal rabbit serum and 35S-methionine (or 14C-leucine) were found to contain intensely radiolabeled alpha-macroglobulins (alpha M) (alpha 1 and alpha 2) on electrophoresis. When human alpha 2 M, instead of rabbit serum, was added to cultures, it also appeared radiolabeled, suggesting that lymphocyte-produced proteins (LyP) formed complexes with serum alpha M. These alpha M-associated LyP were produced in greater quantity when lymphocytes were cultured in the presence of mitogens; they were not produced by cells cultured in the presence of cycloheximide; they were produced primarily by B cells rather than T cells or macrophages. Pretreatment of serum or alpha M with methylamine, enhanced rather than inhibited the formation of LyP-alpha M complexes, a finding which is contrary to that expected if the LyP were a proteinase. Since this methylamine treatment of alpha M also results in the generation of free SH groups from the internal thioester bonds of alpha M, the formation of disulfide bonds between LyP and alpha M was considered. Indeed, (a) the LyP-alpha M complex formation was inhibited by N-ethylmaleimide, aurothiomalate, sodium aurothioglucose or D-penicillamine; (b) blocking the SH groups with NEM, of either culture fluid supernates or serum, had an inhibitory effect on the formation of these complexes; (c) the LyP-alpha M complexes were dissociated by sodium dodecyl sulfate (SDS) only after their reduction with 2-mercaptoethanol (2-ME). Thus, a disulfide bond was formed between alpha M and LyP with free SH groups (SH-LyP). Molecular sieving by high performance liquid chromatography (HPLC) of the serum-free radiolabeled supernates indicated that SH-LyP eluted at a position corresponding to a polypeptide of mol. wt of about 22,000. However, SDS-PAGE of the 22,000 mol. wt HPLC fraction showed that the major protein was approximately mol. wt 11,000 under both reducing and non-reducing conditions. In addition, the SH-LyP reduced by 2-ME from its binding site on alpha 2M had a mol. wt of about 11,000 in SDS-PAGE, suggesting that it was a non-covalent homodimer of mol. wt 11,000 polypeptides. We suggest that alpha 2M as well as SH-LyP may affect the immune system by functioning as SH-reactive agents.

Animals↗

PubMed1989

The relationship between the percentage of circulating B cells, corticosteroid levels, and other immunologic parameters in thermally injured patients.

Thermal injury is known to induce alterations in the immune system, but the precise mechanisms have yet to be elucidated. We investigated the temporal relationship between serum and urine corticosteroid levels, the number of circulating B cells, serum immunoglobulin levels, and delayed hypersensitivity reactions in the postburn period. Fifteen adult patients (mean age, 44 years) admitted with thermal burns greater than 20% body surface area (BSA) (mean, 50%) were evaluated during four postburn periods. Using a bacterial adherence assay in blood smears, we observed an increased percentage of B lymphocytes (20.3%) in the early postburn period compared to normal controls obtained during the same time period (13.1%). The percentage of B cells gradually decreased during the subsequent 4 weeks and was not influenced by the eventual clinical outcome. The changes in B-cell percentage were paralleled by changes in the level of urine 17-hydroxysteroids. Serum IgG concentrations were low during the initial postburn period in survivors and nonsurvivors and returned to normal and above-normal levels in the late postburn period in both groups. The delayed hypersensitivity skin test reactions were also depressed in the immediate postburn period and returned to normal only in the surviving group at the end of the second postburn week. We speculate that the increased endogenous secretion of stress hormones results in an increase in circulating B cells secondary to their release from lymphoid organs and that the normalization of hormone levels as wound healing ensued was associated with the return of B cells to the lymphoid organs. This lymphocyte redistribution may result in polyclonal cellular interactions, with subsequent B-cell activation, and increased IgG production.

Adrenal Cortex Hormones↗

PubMed1986

Increase in proliferation and cytotoxic cell development in human mixed lymphocyte cultures in the presence of very low concentrations of LPS: role of IL-1 and prostaglandin E2.

Lipopolysaccharide (LPS) added to human allogeneic mixed lymphocyte cultures (MLC), even at very low concentrations, increased the level of specific cytotoxicity that developed. Proliferation was also increased by LPS in MLC but no increase was detectable when the allogeneic stimulus was absent. LPS enhanced only low cytotoxic responses while having little effect on naturally high responses. Significant enhancement in cytotoxic response was found within the picogram-nanogram per milliliter range of concentrations of LPS and only when it was added at the initiation of cultures. This early action of low concentrations of LPS suggested that IL-1 was involved. Indeed, a supernatant from silica-treated human mononuclear cells containing IL-1 activity also enhanced cytotoxic and proliferative responses. Aside from increasing IL-1 secretion we also found that LPS significantly increased synthesis and secretion of PGE2 which had a selective inhibitory effect. Namely, addition of indomethacin or flurbiprofen to MLC further enhanced the cytotoxicity of LPS-treated but not that of untreated cultures without increasing the proliferative response. These results suggest a key role for macrophage-derived IL-1 and PGE2 in the regulation of proliferative and cytotoxic responses of T cells. They also suggest that very low amount of LPS may reach the immune system and contribute to the expression of cell-mediated immune responses.

Adult↗

PubMed1986

A low molecular weight proteinase inhibitor produced by T lymphocytes.

A low molecular weight (MW) proteinase inhibitor, between 6500 and 21,500 MW, appeared in the supernatant of rabbit spleen cells cultured at high density for 24 hr. The inhibitor inhibited the enzymatic activity of trypsin for both a high MW natural substrate, fibrinogen, and for a low MW artificial substrate, Chromozym TRY. The low MW proteinase inhibitor is protein in nature and is different, in terms of specificity for enzymes, MW and sensitivity to different physical or chemical treatments, from aprotinin, a low MW proteinase inhibitor (6500 MW) of bovine origin, and from the soybean trypsin inhibitor, a relatively high MW proteinase inhibitor (21,500 MW). The inhibitor was found in the supernatant of purified T cells but not B cells, and its production was increased in the presence of an optimal concentration of Con A. The possibility that this proteinase inhibitor has a role in the regulation of trypsin-like proteinases involved to the immune response remains to be investigated.

Animals↗

PubMed1986

Inactivation of human interleukin-2 (IL-2) by alpha 2-macroglobulin-trypsin complexes.

The loss of the biological activity of interleukin-2 (IL-2, T-cell growth factor) in the presence of alpha 2-macroglobulin-trypsin (alpha 2M.t) complexes has been investigated using an IL-2-dependent cloned 'cytotoxic' murine T-cell line. While reaction mixtures of native alpha 2M, aprotinin or methylamine-treated alpha 2M and IL-2 had no effect on IL-2 activity when incubated at 37 degrees for 5 h, alpha 2M.t (90 nM, [T]:[alpha 2M] = 0.8) inactivated IL-2 at a rate of one-sixth of that of the free enzyme. This effect was abolished by treatment of alpha 2M.t with aprotinin (MW 6500). Soybean trypsin inhibitor coupled to Sepharose 4B was capable of absorbing the IL-2 degrading activity from the trypsin solution. In contrast, alpha 2M.t treated with the solid-phase immobilized soybean trypsin inhibitor continued to inactivate IL-2, but did not degrade a macromolecular substrate (remazol-brilliant blue hide). Thus, IL-2 (MW 15,500) gains access to the active site of the alpha 2M-bound trypsin, resulting in a rapid loss of its biological activity. These observations offer an explanation for the in vitro immunosuppressive effects of alpha 2M.t.

Cell Division↗

PubMed1985

Immunobiological function of normal rabbit synovial cells.

The ability of enzyme-dissociated primary cultures of synovial cells (Sy) to present antigen was investigated. Adult rabbits were immunized in foot pads with bovine serum albumin (BSA) in complete Freund's adjuvant (CFA) or with CFA alone. Four to six weeks later draining popliteal lymph node cells (LNC) and synovial cells were obtained. Synovial cells were cultured overnight with or without antigen. About 20% of these synovial cells had Fc receptors and 15% C3 receptors. As a positive control splenic adherent cells (SAC) were similarly treated. Next day, autologous lymph node cells were added to the extensively washed and irradiated synovial cells or splenic adherent cells. Lymphocyte proliferation was measured by [3H]thymidine uptake. Synovial cells as well as splenic adherent cells induced mixed lymphocyte reaction (MLR) and autologous mixed lymphocyte reaction (AMLR) and effectively presented antigen for specific immune response to the priming antigen. Thus, the synovium contains macrophage-like cells that can effectively interact with lymphocytes and participate in the immune phenomena in the joints of patients with rheumatoid arthritis.

Animals↗

PubMed1985

The use of bacteria as probes for lectins in preparations of solubilized human tonsil cell membranes.

In earlier work we have shown that some bacteria bind naturally to lymphocyte subpopulations and that this binding may be due to lectin-carbohydrate interactions. Here we determined the possibility of using bacteria to probe for these lectins in solubilized tonsil cell membrane preparations. Since lectins are capable of agglutination, we determined the ability of human tonsil cell membrane extract (TCME) to agglutinate bacteria. We used Escherichia coli strain YS57 which does not bind to human lymphocytes and a mutant strain derived from it, E. coli UI 2023, which binds to about 50 percent of human lymphocytes. The UI 2023 was agglutinated while the YS57 was not; this agglutination was not due to antibodies or DNA. When E. coli UI 2023 was treated with periodate, it lost its ability to be agglutinated. The agglutination of E. coli UI 2023 was not blocked by any of the monosaccharides and disaccharides used but was blocked by the E. coli LPS, more specifically, by its carbohydrate moiety. Also, the E. coli UI 2023 absorbed the agglutinating factor while its parental strain, YS57, did not. Sodium dodecylsulfate-polyacrylamide gel electrophoresis of TCME after absorption with bacteria showed that a band around 67kD was absent in the TCME absorbed by E. coli prevented the absorption by E. coli UI 2023 whereas Na2IO4-treated LPS did not. In addition, tonsil cell membrane was radioiodinated before obtaining the TCME; sodium dodecylsulfate-polyacrylamide gel electrophoresis of the radioiodinated TCME recovered after elution from E. coli UI 2023, but not from E. coli YS57, showed again a band around 67 kD.(ABSTRACT TRUNCATED AT 250 WORDS)

Agglutination↗

PubMed1985

Allogeneic lymphocyte stimulation in rabbits: induction of a low MW inhibitor for trypsin and for a concurrently induced alpha-macroglobulin-proteinase complex.

We have shown previously that the i.v. inoculation of allogeneic lymph node cells in rabbits induces the appearance in the serum of an alpha M-serine proteinase complex which behaves in an Ig-turnover assay as any polyclonal B-cell activator (PBA), and that this PBA activity is due to the enzyme. Here, we show that the allogeneic stimulation also induces the appearance in the low molecular weight fraction of the serum (1000-110,000 MW) of an inhibitor which blocks the PBA activity of the complex without affecting the PBA activity of LPS or dextran sulphate. The inhibitor blocked the ability of the enzyme associated with alpha M to degrade Chromozym TRY, a low MW trypsin substrate. The inhibitor also blocked the enzymatic activity of trypsin for large as well as for low MW substrates. Thus, allogeneic stimulation in vivo results in the production, not only of an alpha M-proteinase complex, but also of an inhibitor for this proteinase as well as for trypsin. The appearance of the inhibitor, along with the alpha M-serine proteinase complex as a result of allogeneic stimulation in rabbits, is of interest since a similar alpha M-serine proteinase complex and inhibitor may appear in the serum of patients with rheumatoid arthritis.

Animals↗