A capillary diffusion method for determining hemolytic complement activity in undiluted serum .

A method is presented for measuring the hemolytic activity of undiluted guinea pig serum. Undiluted serum is placed in contact with a column of sensitized sheep red blood cells in an agar matrix in a capillary tube. After incubation, the length of the zone of lysis is measured. Comparison with a standard curve prepared from dilutions of a pool of normal serum allows relative quantitation. Because the serum is not diluted, this method allows detection of reversible inhibitors of the complement system.