Identification of C3 beta chain as the human serum eosinophil cytotoxicity inhibitor.
An eosinophil cytotoxicity inhibitor (ECI) was purified from serum of a human subject with severe allergic dermatitis. Molecular weight of the isolated polypeptide (75,000) and its NH2-terminal amino acid sequence identified it as the beta chain of the C3 complement component (apparently free, but perhaps attached to very small fragments of the alpha chain). Free beta chain, prepared from normal plasma by reduction of C3, inhibited both eosinophil cytotoxicity and neutrophil adherence functions, with half-maximal activity at approximately 250 ng/ml. Apparently free C3 beta chain was detected in certain human biological fluids associated with inflammation; the presence of C3 beta chain correlated with ECI activity. This evidence demonstrates a potential role for free C3 beta chain as a suppressor of eosinophil and neutrophil functions in inflammation.
Department of Rheumatology and Immunology, Brigham and Women's Hospital, Boston, Massachusetts.
M S
MS
Minkoff
W W
WW
Wong
D S
DS
Silberstein
D000595:Amino Acid Sequence; D003176:Complement C3 / Q000032:analysis / Q000302:isolation & purification* / Q000502:physiology; D003602:Cytotoxicity, Immunologic / Q000187:drug effects*; D003877:Dermatitis, Contact / Q000097:blood; D004804:Eosinophils / Q000187:drug effects* / Q000276:immunology; D006801:Humans; D066298:In Vitro Techniques; D008969:Molecular Sequence Data; D008970:Molecular Weight
D003176:Complement C3