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Fibrinogen Binding Inhibits the Fixation of the Third Component of Human Complement on Surface of Groups A, B, C, and G Streptococci
Author(s) -
Chhatwal Gursharan S.,
Dutra Iveraldo S.,
Blobel Hans
Publication year - 1985
Publication title -
microbiology and immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.664
H-Index - 70
eISSN - 1348-0421
pISSN - 0385-5600
DOI - 10.1111/j.1348-0421.1985.tb02961.x
Subject(s) - fibrinogen , complement fixation test , trypsinization , biology , microbiology and biotechnology , biochemistry , antibody , immunology , serology , trypsin , enzyme
Effects of fibrinogen binding to M protein‐positive and ‐negative streptococci on fixation of the third component of human complement (C3) were determined. In all test cultures of serological groups A, B, C, and G fixation of C3 was observed in normal human serum as revealed by quantitative fluorescent immunoassay. Fibrinogen binding inhibited the fixation of C3 on streptococci. The degree of inhibition was proportional to the extent of fibrinogen binding. Thus, inhibition of C3 fixation was most pronounced in strongly fibrinogen‐positive streptococci of groups A, C, and G and not demonstrable in fibrinogen‐negative cultures of groups C and G. Trypsinization of the streptococci destroyed their capacity to bind fibrinogen and consequently the inhibitory effects on C3 fixation. The carboxymethylated α and β chains of fibrinogen moderately inhibited C3 fixation whereas γ chain had no influence. These studies may indicate that fibrinogen binding structures other than M protein could also be involved in streptococcal pathogenicity.