High- and low-affinity antibodies--some observations in relation to polyethylene glycol concentration in immunoturbidimetric assays.

In an immunoturbidimetric assay it is generally accepted that by increasing the polymer concentration the turbidimetric response is increased when all the other parameters are constant. This is true when working with low-affinity antibodies. When working with high-affinity antibodies some assay systems will produce dose-response curves showing decreasing responses with increasing polymer concentrations. These observations are discussed in relation to the time-course of formation of antigen-antibody complexes.