Peptides useful in determining the presence of autoantibodies in patients suffering from rheumatoid arthritis are disclosed.

A method for analyzing a biological sample by antibody profiling for identifying forensic samples or for detecting the presence of an analyte. In an embodiment of the invention, the analyte is a drug, such as marijuana, Cocaine (crystalline tropane alkaloid), methamphetamine, methyltestosterone, or mesterolone. The method comprises attaching antigens to a surface of a solid support in a preselected pattern to form an array wherein locations of the antigens are known; contacting the array with the biological sample such that a portion of antibodies in the sample reacts with and binds to the antigens in the array to form immune complexes; washing away antibodies that do form immune complexes; and detecting the immune complexes, to form an antibody profile. Forensic samples are identified by comparing a sample from an unknown source with a sample from a known source. Further, an assay, such as a test for illegal drug use, can be coupled to a test for identity such that the results of the assay can be positively correlated to the subject's identity.

The present invention stems from the finding that the extracellular domain of CD31 proteins present on blood leukocytes is shed and released in the circulation as a soluble form of CD31. A method for detecting shed CD31 is further disclosed. The invention therefore relates to a method for detecting a shed ectodomain of a transmembrane protein such as CD31 and to the use of such a method as a diagnostic tool. The invention further provides methods for determining whether a candidate protein is part of a molecular complex.

The present invention provides fluidic devices and systems that allow detection of analytes from a biological fluid. The methods and devices are particularly useful for providing point-of-care testing for a variety of medical applications.

Method of enriching specific cells from cellular samples are disclosed, comprising contacting in solution a cellular sample with affinity-tagged ligands (ATLs) each comprising a first ligand linked to an affinity tag, wherein the ligand selectively binds a cellular marker of the rare cells and the affinity tag can be selectively captured by a capture moiety, wherein the affinity tags do not comprise a magnetic particle; and flowing the sample through a microfluidic device comprising the capture moiety to selectively retain ATL-bound cells. Methods for enriching circulating tumor cells, and devices for enriching specific cells from cellular samples are also disclosed.