Peptide arrays for the determination of humoral responses induced by active immunization with a monoclonal antibody against EpCAM

Ex vivo and in vivo capture and deactivation of circulating tumor cells by dual-antibody-coated nanomaterials

Circulating tumor cells (CTCs) have been detected by us and others in cancer patient blood. However, little is known about how to specifically capture and deactivate CTCs in vivo, which may lead to successful metastasis prevention in asymptomatic cancer survivors after surgery. We hypothesize that the dual antibody conjugates may have the advantage of capturing CTCs specifically over their single antibody counterparts. Here we show that the surface-functionalized dendrimers can be sequentially coated with two antibodies directed to surface biomarkers (EpCAM and Slex) of human colorectal CTCs. The dual antibody-coated dendrimers exhibit a significantly enhanced specificity in capturing CTCs in the presence of interfering blood cells, and in both eight-patient bloods and nude mice administered with the labeled CTCs in comparison to their single antibody-coated counterparts. The dual antibody-coated conjugates down-regulate the captured CTCs. This study provides the first conceptual evidence that two antibodies can be biocompatibly conjugated to a nanomaterial to capture and down-regulate CTCs in vivo with the enhanced specificity.

Exploring and profiling protein function with peptide arrays

Development of array technologies started in the late 1980s and was first extensively applied to DNA arrays especially in the genomic field. Today this technique has become a powerful tool for high-throughput approaches in biology and chemistry. Progresses were mainly driven by the human genome project and were associated with the development of several new technologies, which led to the onset of additional "omic" topics like proteomics, glycomics, antibodyomics or lipidomics. The main characteristics of the array technology are (i) spatially addressable immobilization of a huge number of different capture molecules; (ii) probing the array in a simultaneous and highly parallel manner with a biological sample; (iii) tendency towards miniaturization of the arrays; and (iv) software-supported read-out and data analysis. We review some general concepts about peptide arrays on planar supports and point out technical aspects concerning the generation of peptide microarrays. Finally, we discuss recent applications by describing relevant literature.

Yeast cell surface display system for determination of humoral response to active immunization with a monoclonal antibody against EpCAM

Even though an immunogenic formulation of the murine monoclonal anti-EpCAM (epithelian cell adhesion molecule) antibody Mab 17-1A, has been shown to evoke a strong humoral immune response in both, monkey studies and early clinical trials, conventional anti-EpCAM ELISA could not identify anti-EpCAM immune response in relation to treatment with Mab17-1A. In contrast, usage of cellulose membranes prepared by SPOT technology presenting overlapping EpCAM peptides allowed the unequivocal determination of EpCAM related antibodies present in monkeys sera after immunization with IGN101. Based on such contradictory results, it was of high interest to compare obtained data to a different method for better assessment of their possible interpretation. Therefore, in the present studies, some EpCAM peptides, determined as reactive by binding of IgG isolated from sera of treated monkeys on membranes prepared by SPOT technology, were represented on yeast surface using the pYD1 yeast display vector system. Binding of biotinylated IgG from sera was detected with streptavidin-FITC and quantity of binding was determined by FACS measurement. Though using this completely different method, experiments with pre-immune and immune sera of four monkeys exemplarily are comparable to the results obtained by analysis with synthetic peptide arrays.