for the fluorescent dye or incubated with the peroxidase substrate 3 amino 9 ethyl carbazole for peroxidase label the relative antigen level in each row is calculated as the ratio strength of signal minus negative control divided by strength of positive control minus negative control for the 50 level of the positive control this may be represented by the following formula equ1 where negative control background this example illustrates the use of labeled clq as the detection compound the assay is performed using the methods described in example 1 steps a through e followed by f preparation of labeled clq either 50 micrograms of clq or 200 micrograms of serum complement are either radio labeled using lactoperoxidase according to the methods of heusser c et al heusser c m boesman j h nordin and h isliker j of immunol vol 110 p 820 1973 or labeled with peroxidase according to the method described by nakane p k et al nakane p k and a kawaoi j of histochem cytochem vol 22 p 1084 1091 1974 g detection of antigen antibody complexes either labeled clq diluted to 1 100 or labeled complement diluted 1 10 are prepared and 25 microliters are pipetted into each well the plates are incubated for 30 minutes at 25 u00b0 c in a humidified chamber they are then washed 10 times with pbs h detection of antigen antibody clq complexes the plates in step g are then processed by appropriate means for signal detection e g the wells are separated from the plate and counted as described in step h of example 1 the relative antigen level in each row is calculated as in step h of example 1 in either example 1 or 2.