A micromodification of the CH50 test for the classical pathway of complement.

A micromodification of the CH50 assay of Kabat and Mayer is described in which the total reaction volume has been reduced five-fold. This assay utilizes sheep red blood cells pooled from multiple animals rather than from a single animal to avoid screening procedures of red blood cells from individual sheep. Analysis of natural hemolysin activity in normal serum revealed a correlation with elevated CH50 titers. However, this correlation does not appear to effect the clinical interpretation of the results.