Complement activation by cross-linked B cell-membrane IgM
| Autor: | K Ohishi, M Kanoh, H Shinomiya, Y Hitsumoto, S Utsumi |
|---|---|
| Rok vydání: | 1995 |
| Předmět: | |
| Zdroj: | The Journal of Immunology. 154:3173-3179 |
| ISSN: | 1550-6606 0022-1767 |
| DOI: | 10.4049/jimmunol.154.7.3173 |
| Popis: | The B cell membrane IgM (mIgM) occurs in a monomeric form incapable of activating C. However, when cross-linked by a polyvalent ligand, mIgM may activate C by assuming a polymeric structure like secreted IgM. This possibility was tested with CR2- lymphoma cells, which did not activate C spontaneously. When CR2-deficient mIgM(lambda)+ Ramos cells were treated with F(ab')2 goat anti-lambda, then exposed to human serum, a marked C3 deposition took place, as examined by the flow cytometry. Similarly, C3 deposition on mIgM(kappa)+, mIgD(kappa)+ P32 cells was induced by F(ab')2 of either anti-kappa or anti-mu. Anti-delta was without effect, but the C3 deposition resulting from anti-kappa was markedly enhanced after mIgD was modulated by anti-delta. The mIgM-cross-linked cells bound C1q, and C3 deposition on these cells was abrogated by depletion of C1q, but not Factor B nor D, from serum. The C1-binding step of the mIgM-mediated C activation was inhibited by monomeric Fab' of polyclonal anti-mu containing a blocking Ab to the hemolytic activity of human IgM Forssman Ab. A large proportion of C3 deposits on mIgM-cross-linked cells was found to be associated with mIgM in the form of C3dg or C3d. These results demonstrate that cross-linked mIgM indeed triggers the classical pathway of C. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|