Requirement for complement in antibody responses is not explained by the classic pathway activator IgM
2011 (English)In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 108, no 43, 17589-17590 p.Article in journal (Refereed) Published
Animals lacking complement factors C1q, C2, C3, or C4 have severely impaired Ab responses, suggesting a major role for the classic pathway. The classic pathway is primarily initiated by antigen-Ab complexes. Therefore, its role for primary Ab responses seems paradoxical because only low amounts of specific Abs are present in naive animals. A possible explanation could be that the classic pathway is initiated by IgM from naive mice, binding with sufficient avidity to the antigen. To test this hypothesis, a knock-in mouse strain, Cμ13, with a point mutation in the gene encoding the third constant domain of the μ-heavy chain was constructed. These mice produce IgM in which proline in position 436 is substituted with serine, a mutation previously shown to abrogate the ability of mouse IgM to activate complement. Unexpectedly, the Ab response to sheep erythrocytes and keyhole limpet hemocyanin in Cμ13 mice was similar to that in WT mice. Thus, although secreted IgM and the classic pathway activation are both required for the normal primary Ab response, this does not require that IgM activate C. This led us to test Ab responses in animals lacking one of three other endogenous activators of the classic pathway: specific intracellular adhesion molecule-grabbing nonintegrin R1, serum amyloid P component, and C-reactive protein. Ab responses were also normal in these animals.
Place, publisher, year, edition, pages
2011. Vol. 108, no 43, 17589-17590 p.
Basic Medicine Immunology in the medical area Immunology
Research subject Immunology
IdentifiersURN: urn:nbn:se:uu:diva-160601DOI: 10.1073/pnas.1109831108ISI: 000296378100011PubMedID: 21987785OAI: oai:DiVA.org:uu-160601DiVA: diva2:451731
Author summary2011-10-262011-10-262015-11-10Bibliographically approved