Results 1 to 10 of about 697,969 (251)
Multifaceted Activities of Seven Nanobodies against Complement C4b [PDF]
The Journal of Immunology, 2022 Abstract Cleavage of the mammalian plasma protein C4 into C4b initiates opsonization, lysis, and clearance of microbes and damaged host cells by the classical and lectin pathways of the complement system. Dysregulated activation of C4 and other initial components of the classical pathway may cause or aggravate pathologies, such as ...
Karla I De la O Becerra +9 more
europepmc +9 more sources
Human Complement C4B Allotypes and Deficiencies in Selected Cases With Autoimmune Diseases [PDF]
Frontiers in Immunology, 2021 Human complement C4 is one of the most diverse but heritable effectors for humoral immunity. To help understand the roles of C4 in the defense and pathogenesis of autoimmune and inflammatory diseases, we determined the bases of polymorphisms including the frequent genetic deficiency of C4A and/or C4B isotypes. We demonstrated the diversities of C4A and
Danlei Zhou +30 more
europepmc +7 more sources
Increased frequency of the null allele at the complement C4b locus in autism [PDF]
Clinical and Experimental Immunology, 1991 SUMMARY Associations between C4 deficiency and autoimmune disorders have been found over the past several years. Since autism has several autoimmune features, the frequencies of null (no protein produced) alleles at the C4A and C4B loci were studied in 19 subjects with autism and their family members.
W L Warren +6 more
semanticscholar +5 more sources
Increased frequency of complement C4B deficiency in rheumatoid arthritis [PDF]
Arthritis & Rheumatism, 2012 AbstractObjectiveTo assess the copy number variation of complement C4A and C4B genes in patients with rheumatoid arthritis (RA).MethodsDNA samples were obtained from 299 patients and controls and analyzed for copy number variation of total complement C4, C4A, and C4B genes. The results were compared by chi‐square analysis, and odds ratios (ORs) and 95%
Sanna Rosengren +7 more
europepmc +5 more sources
Complement c4b–null alleles in felty's syndrome [PDF]
Arthritis & Rheumatism, 1988 AbstractC4A and C4B allotypes were compared in 20 patients with Felty's syndrome (FS), 52 patients with rheumatoid arthritis (RA), and 55 control subjects. Nineteen of the FS patients had HLA–DR4. A C4B‐null allele was more frequent in the patients with FS (60%) than in either the RA patients (15%) or the control subjects (26%).
Philip A. Dyer +6 more
openaire +4 more sources
Neisserial Lipooligosaccharide Is a Target for Complement Component C4b [PDF]
Journal of Biological Chemistry, 2003 We identified Neisseria meningitidis lipooligosaccharide (LOS) as an acceptor for complement component C4b (C4b). Phosphoethanolamine (PEA) residues on the second heptose (HepII) residue in the LOS core structure formed amide linkages with C4b. PEA at the 6-position of HepII (6-PEA) was more efficient than 3-PEA in binding C4b.
Seppo Meri +13 more
openaire +6 more sources
Degradation of human complement component C4b in the presence of the C4b-binding protein-protein S complex [PDF]
Biochemical Journal, 1983 Vitamin K-dependent protein S and the higher-molecular-weight form of C4b-binding protein (C4bp-high) interact, forming a 1:1 complex with a KD of approx. 1×10(-7) M [Dahlbäck (1983) Biochem. J. 209, 847-856]. In the present study the effect of protein S on the degradation of C4b by Factor I (C3b inactivator) and C4bp was investigated both in fluid ...
B Dahlbäck, B Hildebrand
openaire +2 more sources
Hypomorphic C4B∗ 15 variant of the fourth component of complement [PDF]
FEBS Letters, 1990 We report a rare ‘hypomorphic’ C4 allotype detected during routine screening in controls for the Rogers:1 epitope. C4B∗15 was distinguished by having only faint staining when using polyclonal anti‐C4 antibody on agarose inimunoelectrophoresis (e.g.
Wilma B. Bias +4 more
openaire +3 more sources
Defining Targets for Complement Components C4b and C3b on the Pathogenic Neisseriae [PDF]
Infection and Immunity, 2008 ABSTRACTComplement is a key arm of the innate immune defenses against the pathogenic neisseriae. We previously identified lipooligosaccharide onNeisseria meningitidisas an acceptor for complement C4b. Little is known about other neisserial targets for complement proteins C3 and C4, which covalently attach to bacterial surfaces and initiate opsonization
Lewis, Lisa A. +7 more
openaire +4 more sources
The C4A and C4B Isotypic Forms of Human Complement Fragment C4b Have the Same Intrinsic Affinity for Complement Receptor 1 (CR1/CD35) [PDF]
The Journal of Immunology, 2004 AbstractSeveral previous reports concluded that the C4b fragment of human C4A (C4Ab) binds with higher affinity to CR1 than does C4Bb. Because the isotypic residues, 1101PCPVLD and 1101LSPVIH in C4A and C4B, respectively, are located within the C4d region, one may have expected a direct binding contribution of C4d to the interaction with CR1.
David E. Isenman, Liliana Clemenza
openaire +3 more sources