Source
Department of Clinical Immunology and Transfusion Medicine, University Hospital, Uppsala, Sweden.
Abstract
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.
CONCLUSION:
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.