EVALUATION OF HUMAN-IGG SUBCLASS ASSAYS ON BECKMAN ARRAY

`Automated immunonephelometric assays were developed to measure human IgG subclasses in serum, on the Beckman Array Protein System (APS(R)), with sheep antihuman IgG subclass antisera. The interassay imprecisio n was judged to be satisfactory in each case (CV:IgC(1): 2.3%; IgG(2): 2.9%; IgC(3): 4.0% and IgG(4) 5.4%). The standard curves were found t o be linear in the ranges 1.5-30.0 g/L for IgG(1), 1.5-15.0 g/L for Ig G(2), 0.1-1.0 g/L for IgG(3) and 0.1-1.0 g/L for IgG(4). The lower lim it for quantification of the immunonephelometric assays was 0.50 g/L f or IgG(1), 0.04 g/L for IgG(2), 0.06 g/L for IgG(3) and 0.03 g/L for I gG(4). We found no antigen excess to at least 60.0 g/L for IgG(1) and IgG(2), 3.5 g/L for IgG(3) and 2.0 g/L for IgG(4). Nephelometric resul ts correlated with those of radial immunodiffusion (r=0.96 for IgG(1), r=0.93 for IgG(2), r=0.90 for IgG(3) and r=0.96 for IgG(4)). The reac tion monitored by the Beckman Array Protein System is easy to perform, rapid and precise. The performance makes the immunonephelometric meth od suitable for the determination of IgG subclass concentrations in ro utine analysis.