| 1. |
- Babiker-Mohamed, H, et al.
(författare)
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Alpha 1-microglobulin is mitogenic to human peripheral blood lymphocytes. Regulation by both enhancing and suppressive serum factors
- 1990
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Ingår i: Immunobiology. - 1878-3279. ; 180:2-3, s. 221-234
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Tidskriftsartikel (refereegranskat)abstract
- Human alpha 1-microglobulin (alpha 1-m), a 26 kilodalton serum glycoprotein, was found to exert mitogenic effects on human peripheral blood lymphocytes (PBL) in serum-free medium. Purified T cells, but not B cells, responded with proliferation to alpha 1-m, but only in the presence of monocytes. The mitogenic activity could be partially neutralized by a mouse monoclonal antibody against alpha 1-m. The mitogenicity was species-specific, since alpha 1-m homologues from rats, guinea pigs and rabbits had no effect on human PBL. In a previous study, no effect of alpha 1-m was seen on PBL in the presence of 20% serum, and, therefore, we studied the influence of different concentrations of serum on the alpha 1-m-induced mitogenicity. Thus, human serum enhanced the mitogenic effects of alpha 1-m on human PBL at 1% concentration (v/v) and suppressed the effects at 10%. The suppressing effect of serum at 10%, but not the enhancing effect at 1%, seemed to be conserved among several species. To test the effect of serum proteins of different molecular sizes, human autologous serum was separated by gel chromatography on Sephadex G-200 into four fractions. Fractions 1 and 2 (roughly containing proteins larger than 100 kilodaltons) suppressed the mitogenic effects of alpha 1-m, while fractions 3 and 4 enhanced the stimulation by alpha 1-m, at 0.5% and concentrations above. It is concluded that the mitogenic effect of alpha 1-m on lymphocytes is regulated by several serum factors, both enhancing and suppressive, that does not have any proliferative effect of their own. It can be speculated that the balance between enhancing and suppressing co-factors in the blood determines the degree of the stimulation of lymphocytes by alpha 1-m. This is compatible with an immunomodulatory role for alpha 1-m, in spite of its relatively constant plasma levels in health and disease.
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| 2. |
- Babiker-Mohamed, H, et al.
(författare)
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Characterization of monoclonal anti-alpha 1-microglobulin antibodies : binding strength, binding sites, and inhibition of lymphocyte stimulation
- 1991
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Ingår i: Scandinavian Journal of Immunology. - : Wiley. - 1365-3083 .- 0300-9475. ; 34:5, s. 655-666
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Tidskriftsartikel (refereegranskat)abstract
- Eleven monoclonal antibodies (MoAb) directed against the immunoregulatory plasma glycoprotein alpha 1-microglobulin were characterized. The MoAb were produced in mice immunized with a mixture of alpha 1-microglobulin homologues from man, guinea pig, rat and rabbit. Using radioimmunoassay, western blotting, affinity chromatography, and Scatchard analysis, the affinities and binding sites of the MoAb were analysed. All antibodies were more or less cross-reactive, but most showed a major specificity for one or two of the alpha 1-microglobulin homologues. None of the antibodies was directed against the carbohydrate moiety of alpha 1-microglobulin. Six of the MoAb had high affinity for the antigen and four of these were directed towards the same part of the molecule though differing in their species specificity. Five showed lower affinity for the antigen and were mainly directed towards epitopes on other parts of the molecule. Only some of the antibodies could block the proliferation of lymphocytes induced by human alpha 1-microglobulin. The blocking efficiency of the different antibodies was similar when tested on the stimulation of human or mouse lymphocytes, suggesting that the same part of the alpha 1-microglobulin molecule is responsible in both species. The magnitude of blocking by the different MoAb was not related to their affinities, emphasizing the importance of where on the alpha 1-microglobulin molecule, rather than how strongly, they bind. The binding of the strongest blocking antibody was shown to be directed to a C-terminal peptide of rat alpha 1-microglobulin, indicating that this part of alpha 1-microglobulin is important for the mitogenic effects. Thus the panel of anti-alpha 1-microglobulin MoAb should be a valuable tool for structural and functional studies of alpha 1-microglobulin.
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| 3. |
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| 4. |
- Nilson, B H, et al.
(författare)
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Purification of antibodies using protein L-binding framework structures in the light chain variable domain
- 1993
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Ingår i: Journal of Immunological Methods. - 0022-1759. ; 164:1, s. 33-40
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Tidskriftsartikel (refereegranskat)abstract
- Protein L from the bacterial species Peptostreptococcus magnus binds specifically to the variable domain of Ig light chains, without interfering with the antigen-binding site. In this work a genetically engineered fragment of protein L, including four of the repeated Ig-binding repeat units, was employed for the purification of Ig from various sources. Thus, IgG, IgM, and IgA were purified from human and mouse serum in a single step using protein L-Sepharose affinity chromatography. Moreover, human and mouse monoclonal IgG, IgM, and IgA, and human IgG Fab fragments, as well as a mouse/human chimeric recombinant antibody, could be purified from cultures of hybridoma cells or antibody-producing bacterial cells, with protein L-Sepharose. This was also the case with a humanized mouse antibody, in which mouse hypervariable antigen-binding regions had been introduced into a protein L-binding kappa subtype III human IgG. These experiments demonstrate that it is possible to engineer antibodies and antibody fragments (Fab, Fv) with protein L-binding framework regions, which can then be utilized in a protein L-based purification protocol.
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| 5. |
- Akerström, B, et al.
(författare)
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An intriguing member of the lipocalin protein family : alpha 1-microglobulin
- 1990
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Ingår i: Trends in Biochemical Sciences. - 0968-0004. ; 15:6, s. 3-240
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Forskningsöversikt (refereegranskat)abstract
- The plasma protein alpha 1-microglobulin is a member of the lipocalin protein superfamily. In the last few years, the work on alpha 1-microglobulin has given unexpected and promising new results. Of particular interest are its molecular association with immunoglobulin A and with proteinase inhibitors, and its interactions with the immune system.
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| 6. |
- Babiker-Mohamed, H, et al.
(författare)
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Mitogenic effect of alpha 1-microglobulin on mouse lymphocytes. Evidence of T- and B-cell cooperation, B-cell proliferation, and a low-affinity receptor on mononuclear cells
- 1990
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Ingår i: Scandinavian Journal of Immunology. - : Wiley. - 0300-9475 .- 1365-3083. ; 32:1, s. 37-44
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Tidskriftsartikel (refereegranskat)abstract
- Human alpha 1-m microglobulin (alpha 1-m), a low molecular weight plasma protein, was found to exert mitogenic effects on mouse lymphocytes from lymph nodes and spleen. The stimulatory effects appeared to be strain-restricted: alpha 1-m induced a varying degree of proliferation of lymphocytes from three strains, whereas one strain responded poorly. Experiments with lymphocyte subpopulations showed only weak stimulatory effects of alpha 1-m on purified T and B lymphocytes cultivated alone. The addition of mitomycin-treated cells of the other subpopulation could not restore the proliferative responses in either T or B lymphocytes. Strong stimulations were recorded only when both T and B lymphocytes were present, indicating that the T and B lymphocytes cooperate to achieve the proliferation. However, FACS studies on cultured splenocytes indicated that the proliferating cells are predominantly B lymphocytes. These data extend our earlier findings of a mitogenic effect of alpha 1-m on guinea pig lymphocytes. Furthermore, results were obtained indicating the presence of a receptor on mononuclear cells. Iodine-labelled alpha 1-m was bound to mononuclear cells prepared from spleens, and the binding could be blocked by an excess of non-labelled alpha 1-m. Scatchard plotting of the data gave an equilibrium constant of 0.7 x 10(5)/M for the binding between alpha 1-m and the receptor. Together with the documented inhibitory activity of alpha 1-m on antigen-driven proliferation of lymphocytes, these results suggest an immunoregulatory role for alpha 1-m.
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| 7. |
- Berggård, T, et al.
(författare)
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Histologic distribution and biochemical properties of alpha 1-microglobulin in human placenta
- 1999
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Ingår i: American Journal of Reproductive Immunology. - : Wiley. - 1046-7408. ; 41:1, s. 52-60
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Tidskriftsartikel (refereegranskat)abstract
- PROBLEM: The embryo is protected from immunologic rejection by the mother, possibly accomplished by immunosuppressive molecules located in the placenta. We investigated the distribution and biochemical properties in placenta of the immunosuppressive plasma protein alpha 1-microglobulin.METHOD OF STUDY: Placental alpha 1-microglobulin was investigated by immunohistochemistry and, after extraction, by electrophoresis, immunoblotting and radioimmunoassay.RESULTS: alpha 1-Microglobulin staining was observed in the intervillous fibrin and in syncytiotrophoblasts, especially at sites with syncytial injury. Strongly stained single cells in the intervillous spaces and variably stained intravillous histiocytes were noted. Solubilization of the placenta-matrix fraction and placenta membrane fraction released predominantly the free form of alpha 1-microglobulin, but, additionally, an apparently truncated form from the placenta-membrane fraction. The soluble fraction of placenta contained two novel alpha 1-microglobulin complexes.CONCLUSIONS: The biochemical analysis indicates the presence in placenta of alpha 1-microglobulin forms not found in blood. The histochemical analysis supports the possibility that alpha 1-microglobulin may function as a local immunoregulator in the placenta.
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| 8. |
- Nilson, B, et al.
(författare)
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Cross-reacting monoclonal anti-alpha 1-microglobulin antibodies produced by multi-species immunization and using protein G for the screening assay
- 1987
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Ingår i: Journal of Immunological Methods. - : Elsevier BV. - 0022-1759. ; 99:1, s. 39-45
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Tidskriftsartikel (refereegranskat)abstract
- In order to generate monoclonal antibodies (MAb) directed against the low molecular weight glycoprotein alpha 1-microglobulin, a BALB/c mouse was immunized with a mixture of human, guinea pig, rat and rabbit alpha 1-microglobulin homologues (multi-species immunization) and boosted several times. On day 194, the mouse splenocytes were fused to SP2/0 myeloma cells. The resulting hybridomas were screened for anti-alpha 1-microglobulin activity against the alpha 1-microglobulin mixture or against the individual homologues. For this screening, protein G (the newly described IgG-binding streptococcal protein) was used in a solid-phase radioimmunoassay. The binding of protein G to immobilized antigen-antibody complexes was enhanced by pre-incubation with rabbit anti-mouse immunoglobulin G. The result was a panel of nine established hybridoma lines, all producing unique monoclonal antibodies, of IgG1 or IgG2a class, to alpha 1-microglobulin. The antibodies were not only reactive in solid-phase radioimmunoassay, but they could also immunoprecipitate 125I-labeled soluble alpha 1-microglobulin. Moreover, they reacted specifically with the alpha 1-microglobulin band in Western blots of urinary proteins separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Such monoclonal antibodies are potentially valuable reagents for the further characterization of alpha 1-microglobulin.
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| 9. |
- Åkerström, Bo, et al.
(författare)
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Alpha(1)-microglobulin.
- 2006
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Ingår i: Lipocalins. - 1587062976 ; , s. 110-110
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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