QUANTITATIVE ESTIMATION OF SERUM SS LEVEL - CHANGES UPON DEVELOPMENT OF AUTOANTIBODIES, ENVIRONMENT AND ACUTE INFLAMATION IN INBRED MICE

Abstract

The level of the 4th complement component (C4) was quantitated in sera from several inbred strains of mice of various ages. In NZB and NC mice, which are known to produce autoantibodies spontaneously, the level of C4 increased from 1-6 mo. of age, maintained high C4 levels until 10 mo. but showed a gradual decrease in serum C4 beginning at 1 yr of age. Direct and indirect Coombs'' antibodies were detected after 6 mo. of age in both strains. C4 level in BALB/c and C57BL/6J mice were relatively constant throughout their life span. To determine whether or not antigen-antibody complexes induce the elevation of serum C4 level, rabbit anti-mouse Ig[immunoglobulin]G serum or normal rabbit serum was injected i.v. into BALB/c mice. Sera obtainted at various times were tested for C3 and C4 by single radial immunodiffusion. The C4 level apparently elevated after the injection of rabbit anti-mouse IgG, but C3 levels did not change after the same treatment. Normal rabbit serum did not induce a detectable change in C3 or C4 levels under the conditions used.