STUDY ON C3-LIKE FACTOR IN THE SERUM OF A C3-DEFICIENT SUBJECT

  • 1 January 1984
    • journal article
    • research article
    • Vol. 51  (2) , 239-245
Abstract
Analysis of the serum of an individual having a deficiency of C3 [complement component 3] (C3D) revealed that despite the fact that the C3 could not be detected immunochemically, a small amount of C3 hemolytic activity and total complement activity was indeed present. A study was performed to analyze the C3-like factor, responsible for this C3 activity in C3D serum. The C3-like factor was not neutralized by anti-C3 but was neutralized by anti-C5. The electrophoretic mobility of the C3-like factor corresponded to that of purified C5. C3-like factor had the antigenicity and electrophoretic mobility of C5. This factor was found in the sera of 3 other C3D subjects and even in pooled normal human serum. In cases of C3D, C5 probably compensates for the genetic lack of C3 and serves a protective function. Sensitized erythrocytes (EA) may be lysed by complement components without participation of C3.