Quantification of antibodies to human growth hormone by high-performance protein G affinity chromatography with fluorescence detection.

The technique of high-performance affinity chromatography (HPAC) is applied to the quantitative determination of antibodies to human growth hormone (hGH) in serum from patients. An affinity column consisting of covalently immobilized protein G on a rigid support is used to capture the antibodies. Texas Red labeled hGH (hGH-TR) is used as a fluorescence probe for detecting the anti-hGH antibodies. Calibration curves are established by using a well-characterized monoclonal antibody to hGH (GHC101). The minimum detectable concentration (MDC) of anti-hGH antibody in serum is 250 ng/mL (this represents 10 ng of anti-hGH injected onto the protein G column). Analytical recoveries are 92-110% for seven replicates with 250-4000 ng/mL of GHC101. A precision of 15% relative standard deviation (RSD) can be achieved at the MDC. The precision is better above the detection limit. The linear dynamic range of the method is approximately 2 orders of magnitude. The total fluorescence recovery from the affinity column is greater than or equal to 96%. Sample analysis times are on the order of 20 min. The HPAC technique gives results in absolute units of concentration that correlate well with binding capacity values determined by radioimmunoassay.