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We evaluated a newly developed solid-phase immunoassay (EIA) of terminal deoxynucleotidyl transferase (TdT, EC 2.7.7.3) and compared it with the enzymatic assay of TdT involving DNA polymerase. We assessed the precision, performance characteristics, and clinical efficacy of the EIA procedure, using 249 specimens of peripheral blood and bone marrow and 118 specimens of whole blood. On linear regression analysis of results for these 249 samples as measured by the two procedures, the correlation coefficient was 0.87. Distribution of TdT in mononuclear cells isolated from whole blood and bone marrow of subjects in several disease categories indicated good concordance between the two assay procedures. The EIA procedure is precise, can be performed on whole blood without first isolating mononuclear cells, is nonisotopic, and shows potential as a quantitative indicator for the differential diagnosis and monitoring of human leukemia.

We evaluated a newly developed solid-phase immunoassay (EIA) of terminal deoxynucleotidyl transferase (TdT, EC 2.7.7.3) and compared it with the enzymatic assay of TdT involving DNA polymerase. We assessed the precision, performance characteristics, and clinical efficacy of the EIA procedure, using 249 specimens of peripheral blood and bone marrow and 118 specimens of whole blood. On linear regression analysis of results for these 249 samples as measured by the two procedures, the correlation coefficient was 0.87. Distribution of TdT in mononuclear cells isolated from whole blood and bone marrow of subjects in several disease categories indicated good concordance between the two assay procedures. The EIA procedure is precise, can be performed on whole blood without first isolating mononuclear cells, is nonisotopic, and shows potential as a quantitative indicator for the differential diagnosis and monitoring of human leukemia.

Radioimmunoprecipitation (RIP), an antigen-binding method, was used to measure antibody to the benzylpenicilloyl (BPO) determinant. In this method radiolabeled BPO-conjugates were added to anti-BPO (step 1) and the resulting soluble antigen-antibody complexes were precipitated by an excess of anti-immunoglobulin (step 2). Various parameters affecting the reactions in RIP, including the times of incubation in steps 1 and 2, ph, salt concentration, number of BPO groups per molecule of carrier protein, and presence of divalent cations, were examined. The sensitivity of RIP also was determined; concentrations of anti-BPO of the order of 0·08 to 0·8 mμg Ab N/ml could be detected. By titrating anti-BPO with increasing amounts of radiolabeled BPO-conjugates, maximal binding values could be determined and used to provide weight estimates of antibody. With amounts of antibody in the range 0·8 to 3·2 μg N, good agreement was found between the amount of antibody determined by quantiative precipitin analysis and that found by RIP. However, in the range 0·08 to 800 mμg N, quantities of antibody determined by RIP were significantly less than those determined by the quantitative precipitin method. This discrepancy was related to the low molar concentrations of antigen used to measure antibody in this range, which are insufficient to drive the equilibrium reaction between antigen and antibody to completion. Finally, the average intrinsic association constant ( K o estimated by RIP was in the same range as that determined by fluorescence polarization.

The titers of antibodies to the benzylpenicilloyl antigenic determinant are increased with specific antiserum to immunoglobulin D, as shown by the enhancement method. This increase in titer is blocked by purified immunoglobulins D protein but not by immunoglobulins of the other four classes.