Enzyme immunochromatography--a quantitative immunoassay requiring no instrumentation.

We describe a novel test-strip immunoassay for quantifying drugs in biological fluids. This enzyme immunochromatographic ("immunograph") method combines many features of the enzyme-channeling homogeneous immunoassay with immunochromatography and capillary migration to provide a non-separation, non-instrumental assay for theophylline in which quantification is based on the spatial distribution of enzyme label rather than on the modulation of enzyme activity. Sample antigen and hapten-enzyme conjugate are combined and moved by capillary action up a paper strip on which specific antibody has been immobilized. After color development, the assay result is evaluated by measuring the height of the colored zone on the test strip. Quantification is not a function of enzyme activity, so the method is relatively insensitive to sample matrix effects, enzyme instability, temperature, and incubation timing. Either whole blood or plasma can be used as sample. Results correlate well with those by established instrumental methods. The simple, rapid (15 min), two-incubation protocol is well suited for on-site testing in non-laboratory environments.

Comparison of different antinucleic acid antibody spectrotypes in spontaneous, induced, and murine lupus.

Sera from patients with systemic lupus erythematosus and from mice spontaneously developing lupus were subjected to isoelectric focusing by a microsucrose gradient method. The spectrotypes of human antibodies to native DNA, denatured DNA, and polyriboadenylic acid (poly A) were compared. Antibodies to native DNA and denatured DNA focused into two regions whose boundaries were pH 5.0-7.0 and pH 8.5-10.0. Antinative DNA antibodies were more homogeneous than antidenatured DNA antibodies. Anti-DNA antibodies in cryoglobulins showed more restriction than those present in serum. There was no relationship between spectrotype and pattern of disease expression. Murine antibodies to native DNA were more heterogeneous than human anti-DNA antibodies. The spectrotypes of antidenatured DNA antibodies from patients with systemic lupus erythematosus or drug induced lupus, or from an immunized rabbit, were similar. Likewise, antibodies to poly A were similar in both human and murine lupus. In contrast to anti-DNA, antibodies to poly A were restricted and focused only in the alkaline range (pH 9.5-10.0). The spectrotype of antipoly A antibodies induced by lipopolysaccharide were comparable but had an additional small band at pH 6.2. Our results suggest unique antibody spectrotypes with varying degrees of restriction for different nucleic acid antigens. Furthermore, spontaneous and induced autoantibodies have similar spectrotypes. Thus, the B cell clones producing antinucleic acid antibodies may be similar whether they are activated spontaneously, following immunization, or as a consequence of polyclonal stimulation.