Comparative sensitivity of two hemagglutination inhibition immunoassays for fibrinolytic degradation products in human serum.

A new modification of hemagglutination inhibition immunoassay for measuring fibrinogen/fibrin degradation products (FDP) using glutaraldehyde as a coupling reagent was introduced. This method was compared with the tanned-red-cell hemagglutination inhibition immunoassay (TRCHII). Sheep erythrocytes (SRBC) were sensitized with fragment D or E, respectively. The procedure of sensitizing SRBC is simple and can be achieved within 2 hrs. The sensitized SRBC stored at 4 degrees C for 6 months did not lose their activities. The sensitivities for assaying D and E relative FDP were 0.32 mug/ml, respectively, which were slightly better than those of TRCHII. This represents the first adaptation of glutaraldehyde erythrocyte hemagglutination inhibition immunoassay (GEHII) for the estimation of FDP employing either microtiter plate or test tube. The microtechnique and test tube method were found to be essentially equivalent. The FDP level in the sera of normal individuals and patients suspected of elevation of FDP were assayed by both TRCHII and GEHII. By linear least squares analysis, the results show a significant correlation between these two methods. These results indicate GEHII is a simple, rapid and sensitive immunoassay for FDP in human serum.