Multiplex determination of antigen specific antibodies with cell binding capability in a self-driven microfluidic system

Antibodies, induced during infections or in autoimmune diseases, exert their protective or destructive effects as part of an orchestrated system that contains several other immune system related proteins and cells. Accordingly immunological assessment of the humoral immune response should include not only the determination of antigen specific antibody level but also the capability of binding to effector cells. We designed and fabricated a polymer based modular autonomous capillary device with an integrated protein microarray that fulfills this need and enables simple, robust detection of antigen specific anti- bodies through their effector cell binding capability. Serum samples derived from rheumatoid arthritis patients, U937 monocytoid cells and cell stain were sequentially introduced into the self-driven device with disease specific printed citrullinated peptide antigens. The number of bound cells was determined by brightfield microscopic imaging. We found strong positive correlation between antibody level deter- mined by conventional protein microarray technology and binding frequency of U937 cells. Detection by U937 cells was more sensitive than with secondary antibodies for one peptide antigen and less than 13 CV% was experienced in the reproducibility of the measurement.