The effect of storage of antigen-coated polystyrene microwells on the detection of antibodies against Borrelia burgdorferi by enzyme immunoassay (EIA).

Qualitative and quantitative changes in the antigenic mosaic of coated solid-phase matrices occurring during storage may have a pronounced effect on the comparability of results obtained by enzyme immunoassay (EIA). We have used, as a model antigen for studying the effects of storage, a sonic extract of Borrelia burgdorferi and a totally automatic EIA procedure. The IgM antibody concentrations of the sera originally determined to be high decreased by almost one half during 1 week's storage of the solid phase of 4 degrees C. In contrast, the IgM values of other sera, originally measured at medium or low, doubled upon storage. Thus, after storage the rank order of the sera was markedly affected compared to the values obtained with antigen freshly applied to the wells. In parallel determinations of IgG antibody levels the EIU relative unitage values of the test sera generally remained constant upon storage. The only exception was the serum with the highest original antibody concentration. Its relative antibody unitage more than tripled over the storage time. It is recommended that the coating of solid-phase matrices should be done immediately before each run in all EIAs where microbial extracts are used as antigens.