Immunophenotyping of acute leukemias using a quartz crystal microbalance and monoclonal antibody-coated magnetic microspheres

Immunophenotyping, which utilizes panels of lineage-associated monoclonal antibodies to recognize clusters of differentiation (CD) antigens expressed on various leukocytes, plays a key role in the clinical diagnosis of acute leukemias. In this paper, a rapid, simple, and automatic immunophenotyping technique for acute leukemias has been initially proposed by incorporating immunomagnetic separation and quartz crystal microbalance (QCM) measurement. Core-shell paramagnetic microspheres of silica-coated ZnFe2O4 were newly fabricated following a W/O microemulsion route and further functionalized for anchoring separately CD antibodies of lineage-different leukocytes. The resultant immunomagnetic microspheres were introduced, in turn, to capture target leukocytes from the samples and were magnetically accumulated onto the protein A-modified QCM to be analyzed. The response characteristics of the developed QCM system for immunophenotyping various lineage-defined leukocytes were investigated in detail. Results indicate that this new technique can allow for easy and clear identification of acute leukocytes of lymphoid and myeloid origins as well as their subsets. It may also permit the quantitative determination of acute leukocytes with cell concentration down to approximately 10(3) cells mL(-1). Moreover, the applicable feasibility of the QCM immunophenotyping method was validated through assessing a number of clinical specimens, which phenotypes are in acceptable agreement with those obtained by the immunoenzyme assay clinically used for this purpose.