WEAK A BLOOD SUBGROUP DISCRIMINATION BY A RHEOOPTICAL METHOD - A NEW APPLICATION OF LASER BACKSCATTERING

Laser backscattering is an excellent tool to investigate size and conc entration of suspended particles. It was successfully applied to the a nalysis of erythrocyte aggregation. A method is proposed that applies laser backscattering to the evaluation of the strength of the immunolo gic erythrocyte agglutination by approaching the energy required for t he mechanical dissociation of agglutinates. Mills and Snabre have prop osed a theory of laser backscattering for erythrocyte aggregation anal ysis. It is applied here to analyze the dissociation process of erythr ocyte agglutinates performed by imposing a constant shear rate to the agglutinate suspension in a couette viscometer until a dispersion of i solated red cells is attained. Experimental verifications of the metho d were performed on the erythrocytes of the ABO group reacting against an anti-A test serum in twofold series dilutions. Spent energy is app roached by a numerical process carried out on the backscattered intens ity data registered during mechanical dissociation. Velocities of aggl utination and dissociation lead to the calculation of dissociation par ameters. These values are used to evaluate the strength of the immunol ogical reaction and to discriminate weak subgroups of ABO system.