Characterization of Antibodies against Human Red Blood Cell Antigens with a Rheo-Optical Approach

Background: To define parameters characterizing monoclonal antibody (mAb) agglutination properties is a topic of high relevance in diagnostic immunohematology. Material and Methods: Laser backscattering is used to analyze the agglutinates’ dissociation process. The suspension in a Couette flow is exposed to different shear forces, and the backscattering light intensity is quantified. Parameters characterizing antibody agglutination properties are obtained. Results: Parameters obtained by the rheo-optical method characterize antibodies agglutination properties. They are proportional to antibody concentration. The approaches allows to classify mAb according to the agglutination strength as high-, medium- and low-strength antibodies and were successfully applied to determine parameters for polyclonal (anti-A, anti-D) and monoclonal (anti-A, anti-B, anti-AB, anti-H, anti-Le, anti-P, anti-M, anti-N, anti-GPA and anti- T) antibodies. The first approach was also used to discriminate blood group A phenotypes. Estimation of the linear regression slope is an interesting parameter to evaluate the strength of the reaction which may depend on density of antigenic sites on the cell membrane but also on the specificity of the cell antigen. Conclusions: The biophysical approach presented in this work can provide new and interesting information about intercellular adhesion and, consequently, may suggest new questions on the energies involved in immunological red blood cell agglutination. Such information on the energy existing between membranes agglutinated by mAb may help to understand many important physiological and pathological phenomena, but, particularly, it will be useful in the quality control of monoclonal antibodies.