Hereditary dysfunction of the third component of complement associated with a systemic lupus erythematosus-like syndrome and meningococcal meningitis.
OBJECTIVE
We describe a dysfunction of C3 in a patient with a systemic lupus erythematosus (SLE)-like syndrome. Alternative pathway complement function was absent, but classical pathway complement function was partially intact.


METHODS
We used functional, preparative, and immunochemical techniques in the study.


RESULTS
The patient's C3 proved normally susceptible to trypsin proteolysis and partially resistant to classical pathway, but completely resistant to alternative pathway, convertase-dependent cleavage.


CONCLUSIONS
The dysfunction, thus, was caused by a failure of C3 to interact with the C3 convertases, rather than by a lack of a proteinase-sensitive cleavage site in the deficient protein.
Nilsson
U R
UR
Department of Clinical Immunology and Transfusion Medicine, University Hospital, Uppsala, Sweden.
Nilsson
B
B
Storm
K E
KE
Sjölin-Forsberg
G
G
Hällgren
R
R
D000328:Adult; D003167:Complement Activation; D003176:Complement C3 / Q000235:genetics* / Q000502:physiology; D003170:Complement Pathway, Alternative; D003171:Complement Pathway, Classical; D005260:Female; D030342:Genetic Diseases, Inborn / Q000276:immunology / Q000503:physiopathology*; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000150:complications* / Q000276:immunology; D008585:Meningitis, Meningococcal / Q000150:complications* / Q000276:immunology; D010641:Phenotype
D003176:Complement C3