1994 Fiscal Year Final Research Report Summary
A novel lectin-dependent activation pathway of complement
| Project/Area Number |
06044189
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| Research Category |
Grant-in-Aid for international Scientific Research
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| Allocation Type | Single-year Grants |
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| Section | Joint Research |
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| Research Institution | Fukushima Medical College |
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Principal Investigator |
FUJITA Teizo Department of Biochemistry, Fukushima Medical College, 医学部, 教授 (20134223)
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| Co-Investigator(Kenkyū-buntansha) |
ターナー マルコム ロンドン大学, 小児保健研究所, 教授
リード ケネス オックスフォード大学, MRC, 教授
EZEKOWITZ Alan Department of Pediatrics, Harverd Medical School, 医学部, 准教授
MIZUOCHI Tsuguo Department of Applied Chemistry, Tokai University, 工学部, 教授 (90133149)
KOBAYASHI Kunihiko Department of Pediatrics, Hokkaido University School of Medicine, 医学部, 教授 (60091451)
MATSUSHITA Misao Department of Biochemistry, Fukushima Medical College, 医学部, 講師 (00165812)
TURNER Malcolm w The Institute of Child Health, University of London
REID Kenneth b m MRC,University of Oxford
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| Project Period (FY) |
1994
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| Keywords | MBP / MASP / C1 / Reuhmatoid arthritis / IgG |
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| Research Abstract |
Serum mannose-binding protein(MBP)is a C-type lectin capable of activating the complement system (the lectin pathway). A serine protease designated MASP (MBP-associated serine protease) is involved in the activation by MBP,exerting C4-and C2-activating capacity when bound to MBP on its ligands.
1.To clarify the mechanisms by which C1r/C1s is substitute for MASP in the activation of the lectin patheway, we measured the affinity of C1r/C1s or MASP to C1q and MBP in a Biacore apparatus. The results indicate that the affinities of the four possible mixtures are very similar. Since MBP-MASP and C1q-C1r/C1s complex were present in plasma, the other factors would influence the interaction of MBP and C1r/C1s.
2.We inverstigated reconstitution of recombinant MBPs and MASP for exhibiting complement activation. Wild type rMBP was found to be able to be associated with MASP,resulting in complement activation, whereas rMBP_D in which glycine is substituted with asparatic acid in the fifth collagen re
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peat and responsible for the complement-dependent opsonic defect is unable to activate complement when incubated with MASP.These results indicate that lack of complement-activating capacity of rMBP_D might be due to inability of association with MASP.
3.To evalute the role of MBP in rheumatoid arthritis, we characterized the MBP-binding substances in sera of these patients. An enzyme linked immunosorbent assay (ELISA) was performed to detect the MBP-binding substances in sera of patients with RA.Sera of patients with RA showed higher MBP binding compared with those of normal controls. To characterize the MBP-binding substances, we applied sera of two patients with RA to an immobilized MBP column. Both IgG and IgM-RF were found in the binding substances of patients with RA eluted from MBP-column, whereas IgG was found in that of normal control. The results of molecular sieve chromatography showed that the binding substances of patients with RA consisted of immune complexes containing IgG and IgM-RF.These binding substances were specifically bound to MBP,and then MBP-MASP complexes consumed C4. Therefore, MBP binds to immune complexes consisting of IgG and IgM-RF,and probably recognizes either mannose of IgM-RF or N-acethylglucosamine of agalacto IgG.The lectin pathway would be activated in sera of patients with RA. Less
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Research Products
(4 results)
