Capillary Nano-immunoassay for Quantification of Proteins from CD138-purified Myeloma Cells.

Protein analysis in bone marrow samples from patients with multiple myeloma (MM) has been limited by the low concentration of proteins obtained after CD138+ cell selection. A novel approach based on capillary nano-immunoassay could make it possible to quantify dozens of proteins from each CD138+ purified MM sample in an automated manner. Up to now, the knowledge of protein level in those cells was limited because a relatively small quantity of sample is available after the diagnostic procedure. Moreover, the sample often is required for nucleic acids analysis. We have developed the procedure for obtaining proteins from bone marrow samples preserved in RLT+ buffer, and we have successfully applied this approach for the quantification of proteins in the setting of patients with MM. Proteins are extracted from RLT+ buffer, the content is quantified by total protein assay with WES machine and finally, the particular protein expression level is evaluated using specific antibodies by capillary nano-immunoassay with WES machine. The present protocol enables us to quantify many proteins from a limited amount of sample, without losing the opportunity to obtain nucleic acids at the same time. Proteins are quantified automatically in an assay with a low probability of human errors, which makes it a useful tool for biomarkers development.