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The intricate system of serum complement proteins provides resistance to infection. The spleen and complement C3 provide resistance against blood-borne S. pneumoniae infection. To better understand the mechanisms involved, we studied SIGN-R1, a lectin that captures microbial polysaccharides in spleen marginal zone. We found that SIGN-R1 directly bound the complement C1 subcomponent, C1q, and assembled a C3 convertase, but without the traditional requirement for either antibody or factor B. Therefore the transmembrane lectin SIGN-R1 contributes to innate resistance by an unusual C3 activation pathway, unraveling the novel and 4th complement activation pathway (1) It has been reported that sialylation on Fc doamin of immunogloublin is critical for the effect of intravenous immunoglobulin (IVIG) and seems to be mediated by lectins which are expressed on splenic marginal zone macrophages (2,3). And they demonstrated that SIGN-R1 preferentially binds to 2,6-sialylated Fc compared with similarly sialylated, biantennary glycoproteins, thus suggesting that a specific binding site is created by the sialylation of IgG Fc (4). Moreover, they showed that a human homologue of SIGN-R1, DC-SIGN, displays a similar binding specificity to SIGN-R1 but differs in its cellular distribution, potentially accounting for some of the species differences observed in IVIG protection (5). However, the function of DC-SIGN in IVIG effects is controversial now, given that DC-SIGN and alpha2,6-sialylated IgG Fc interaction is dispensable for the anti-inflammatory activity of IVIg on human dendritic cells (6). Autoantibody is the principal mediators of autoimmune disease. IVIG is a milestone of the therapy of autoimmune disease. Now we hypothesize that complement systems are essential for the recognition of the sialylated Fc domain of immunoglobulin by SIGN-R1 or DC-SIGN, which lead to various IVIG effects or anti-inflammatory effects. In our further studies, we hope to further characterize the SIGN-R1-mediated IVIG effects and these works could lead to develop a potential therapeutic target against several autoimmune diseases.

저자

• Young Sun Kang [ Dept. Biomedical Science & Technology, Institute of Biomedical Science & Technology (IBST), Laboratory of innate immunity, Konkuk University ]

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간행물

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• 간행물명

  한국당과학회 학술대회

• 간기

  연간

• 수록기간

  2006~2022

• 십진분류

  KDC 517 DDC 614